Quarterly Fund Fact Sheets March 31, Retirement Share Classes

Quarterly Fund Fact Sheets March 31, 2018 Retirement Share Classes

About Thornburg Investment Management It s more than what we do. It s how we do it. At Thornburg, we are very different in how we think, invest, and are structured. We believe this difference is what makes us successful in helping individuals reach their long-term financial goals. How we How we How we re Flexible Perspective Our perspective on investment opportunities is more flexible than most, viewing a wide range of opportunities beyond conventional boundaries to find hidden value. Collaboration Collectively, we hone ideas via borderless cross-pollination for better judgment and better results. Portfolio Construction Disciplined construction guided more by our convictions than convention. CONVICTION Thorough analysis and our relative-value framework lead to conviction in our securities selection. UNCONVENTIONAL Active management means we seek the best value for our clients rather than using conventional benchmarks as our starting point. Structured for Excellence How we think and how we invest is made possible by how we re structured. TEAM APPROACH FAR FROM THE HERD ACCESS & TRANSPARENCY

Table of Contents We offer a variety of investment strategies that can serve as important components of an investor s diversified portfolio. Global Equity PAGE Investment Income Builder Fund... 3 Global Opportunities Fund.... 5 International Equity International Value Fund.... 7 International Growth Fund......................................................... 9 Developing World Fund... 11 Domestic Equity Value Fund... 13 Core Growth Fund.... 15 Global Fixed Income Limited Term U.S. Government Fund... 17 Limited Term Income Fund... 18 Strategic Income Fund.... 19

Thornburg Investment Income Builder Fund MARCH 31, 2018 Investment Strategy The Fund invests in companies (both in the U.S. and abroad) with histories of paying dividends and showing the capacity to increase them. To provide additional income, the Fund may invest in debt obligations of any kind. Investment Objective The Fund s primary investment goal is to provide a level of current income which exceeds the average yield on U.S. stocks generally, and which will generally grow, subject to periodic fl uctuations, over the years on a per share basis. The Fund s secondary investment goal is longterm capital appreciation. There is no guarantee that the Fund will meet its objectives. Portfolio Managers Jason Brady, CFA Ben Kirby, CFA Brian McMahon Supported by the entire Thornburg investment team. Portfolio Composition Domestic Equity 32.1% Foreign Equity 58.7% Domestic Corporate Bonds 4.0% Domestic Other Bonds 0.6% Foreign Bonds 2.9% Cash & Cash Equivalents 1.6% Capitalization Exposure Small Cap (< $2.5 B)2.8% Mid Cap ($2.5-12 B)8.0% Large Cap (> $12 B) 89.2% As a percentage of common stocks Symbols and Cusips R3 Shares TIBRX 885-215-384 R4 Shares TIBGX 885-215-186 R5 Shares TIBMX 885-215-236 R6 Shares TIBOX 885-216-663 Key Portfolio Attributes Total Assets $15.4 B Equity Statistics Portfolio P/E Trailing 12 months*12.7x Median Market Cap* $41.7 B Holdings78 7-Year Beta (A shares vs. MSCI World)*0.69 Active Share (vs. MSCI World; equities only)*90% Average Annual Total Returns RETIREMENT SHARE CLASSES R3 Shares** (Incep: 2/1/05 ) -2.57% 7.65% 3.57% 5.20% 5.48% 9.15% R4 Shares** (Incep: 2/1/08 ) -2.53% 7.75% 3.66% 5.31% 5.56% 9.29% R5 Shares** (Incep: 2/1/07 )-2.38% 8.20% 4.11% 5.74% 6.00% 9.73% R6 Shares** (Incep: 4/10/17 )-2.33% 8.16% 4.17% 5.84% 6.09% 9.78% Blended Index (Since 12/24/02 ) -1.27% 10.44% 6.36% 7.79% 5.60% 7.63% Returns for less than one year are not annualized. 75% MSCI World Index and 25% Bloomberg Barclays U.S. Aggregate Bond Index ** Prior to inception of this share class, performance is hypothetical and was calculated from actual returns of the class A shares adjusted for the expenses of the newer share class. Performance data shown represents past performance and is no guarantee of future results. Investment return and principal value will fluctuate so shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than quoted. For performance current to the most recent month end, visit thornburg.com or call 877-215-1330. There is no sales charge for this class of shares. The total annual fund operating expenses are as follows: R3 shares, 1.72%; R4 shares, 1.67%; R5 shares, 1.32%; R6 shares, 1.32%. Thornburg Investment Management and/or Thornburg Securities Corporation have contractually agreed to waive fees and reimburse expenses through at least February 1, 2019, for some of the share classes, resulting in net expense ratios of the following: R3 shares, 1.70%; R4 shares, 1.60%; R5 shares, 1.19%; R6 shares, 1.00%. For more detailed information on fund expenses and waivers/reimbursements please see the fund s prospectus. Hypothetical Growth of $10,000 $50,000 $40,000 $30,000 $20,000 $10,000 $0 Dec-24-02 R6 Shares $41,602 R5 Shares $41,337 R4 Shares $38,848 R3 Shares $38,082 Blended Index $30,732 Dec-04 Dec-06 Dec-08 Fixed Income Statistics Average Maturity12.1 Yrs Effective Duration4.4 Yrs Number of Bonds96 * Source: FactSet YTD 1-YR 3-YR 5-YR 10-YR Dec-10 Dec-12 Dec-14 SINCE A SHARE INCEPTION (12/24/02)** Mar-18 The Hypothetical Growth of $10,000 graph reflects reinvestment of dividends and capital gains, if any, as well as all fees and expenses. 3

Sector Allocation (as of 3/31/18, percent of equities) Financials 28.0% Telecommunication Services 14.5% Energy 12.5% Health Care 8.5% Industrials 7.0% Consumer Staples 6.5% Information Technology 6.2% Consumer Discretionary 5.8% Utilities 3.8% Real Estate 3.5% Materials 3.1% Unassigned 0.7% Top Ten Equity Positions (as of 2/28/18, percent of portfolio) CME Group, Inc. 4.0% China Mobile Ltd. 3.8% Royal Dutch Shell plc 3.4% JPMorgan Chase & Co. 3.2% Orange SA 2.8% NN Group NV 2.7% Taiwan Semiconductor Mfg Co. Ltd. 2.6% Novartis AG 2.4% Roche Holding AG 2.3% The Home Depot, Inc. 2.3% Credit Quality Breakout (as of 3/31/18, percent of debt obligations) Investment Grade 41.8% Below Investment Grade 53.3% Not Rated 5.0% Top Ten Industry Groups (as of 3/31/18, percent of equities) Telecommunication Services 14.5% Diversifi ed Financials 13.6% Energy 12.5% Banks 9.2% Pharma, Biotech & Life Sciences 8.5% Semiconductors & Equipment 5.4% Insurance 5.2% Food, Beverage & Tobacco 4.7% Capital Goods 4.1% Utilities 3.8% Please visit thornburg.com for latest portfolio manager commentary. Important Information Top Ten Bond Positions (as of 2/28/18, percent of portfolio) Telefonica Emisiones SAU 0.7% The Williams Companies, Inc. 0.4% Digicel Ltd. 0.3% QBE Insurance Group Ltd. 0.3% Transcontinental Gas Pipe Line Co., LLC 0.3% Investments carry risks, including possible loss of principal. Additional risks may be associated with investments outside the United States, especially in emerging markets, including currency fluctuations, illiquidity, volatility, and political and economic risks. Investments in small- and mid-capitalization companies may increase the risk of greater price fluctuations. Portfolios investing in bonds have the same interest rate, inflation, and credit risks that are associated with the underlying bonds. The value of bonds will fluctuate relative to changes in interest rates, decreasing when interest rates rise. Investments in the Fund are not FDIC insured, nor are they bank deposits or guaranteed by a bank or any other entity. This class of shares is limited to retirement platforms only. Portfolio attributes and holdings can and do vary. A bond credit rating assesses the financial ability of a debt issuer to make timely payments of principal and interest. Ratings of AAA (the highest), AA, A, and BBB are investment-grade quality. Ratings of BB, B, CCC, CC, C and D (the lowest) are considered below investment grade, speculative grade, or junk bonds. Credit quality ratings for Thornburg Investment Income Builder used ratings from Moody s Investors Service. Where Moody s ratings are not available, we have used Standard & Poor s ratings. Where neither rating is available, we have used ratings from other nationally recognized statistical rating organizations (NRSROs). Before investing, carefully consider the Fund s investment goals, risks, charges, and expenses. For a prospectus or summary prospectus containing this and other information, contact your financial advisor or visit thornburg.com. Read it carefully before investing. Glossary Active Share is a measure of the percentage of stock holdings in a manager s portfolio that differ from the benchmark index. It is exclusive to equity holdings. Beta is a measure of market-related risk. Less than one means the portfolio is less volatile than the index, while greater than one indicates more volatility than the index. Effective Duration is a bond s sensitivity to interest rates, incorporating the embedded option features, such as call provisions. Bonds with longer durations experience greater price volatility than bonds with shorter durations. The Blended Index is composed of 25% Bloomberg Barclays U.S. Aggregate Bond Index and 75% MSCI World Index. The Bloomberg Barclays U.S. Aggregate Bond Index is composed of approximately 8,000 publicly traded bonds including U.S. government, mortgage-backed, corporate and Yankee bonds. The index is weighted by the market value of the bonds included in the index. The MSCI World Index is an unmanaged market-weighted index that consists of securities traded in 23 of the world s most developed countries. Securities are listed on exchanges in the U.S., Europe, Canada, Australia, New Zealand, and the Far East. The index is calculated with net dividends reinvested, in U.S. dollars. Indices do not take into account fees and expenses. Investors cannot make direct investments in an index. Thornburg Securities Corporation, Distributor 2300 North Ridgetop Road Santa Fe, New Mexico 87506 877.215.1330 www.thornburg.com Credit Quality Ratings (as of 3/31/18 percent of debt obligations) AAA0.1% AA0.0% A4.0% BBB37.8% BB27.2% B19.7% CCC6.0% CC0.0% C0.0% D0.4% Not Rated5.0% 4/20/18 TH646 4

Thornburg Global Opportunities Fund MARCH 31, 2018 Investment Strategy The Fund invests in equity securities from around the world. A fl exible mandate allows the Fund to pursue long-term performance using a broad approach to geography and market capitalization. Investment Objective The Fund seeks long-term capital appreciation by investing in equity and debt securities of all types from issuers around the world. There is no guarantee that the Fund will meet its objectives. Portfolio Managers Brian McMahon Vinson Walden, CFA Supported by the entire Thornburg investment team. Key Portfolio Attributes Portfolio P/E Trailing 12 months*14.3x Portfolio Price to Cash Flow*8.9x Portfolio Price to Book Value*1.7x Median Market Cap* $29.6 B 7-Yr Beta (A shares vs. MSCI ACWI)*1.00 Holdings30 Fund Assets $2.4 B Active Share (vs. MSCI ACWI)*96% Cash & Cash Equivalents5.6% * Source: FactSet Average Annual Total Returns RETIREMENT SHARE CLASSES Capitalization Exposure Small 2.8% Mid 20.9% Large 76.3% Small Cap (< $2.5 B); Mid Cap ($2.5 12 B); Large Cap (> $12 B) Charts may not add up to 100% due to rounding. YTD 1-YR 3-YR 5-YR 10-YR SINCE A SHARE INCEPTION (7/28/06)** R4 Shares** (Incep: 2/1/08 )-5.56% 7.11% 4.05% 11.05% 7.19% 9.79% R5 Shares** (Incep: 2/1/08 )-5.45% 7.55% 4.48% 11.51% 7.65% 10.26% R6 Shares** (Incep: 4/10/17 )-5.44% 7.70% 4.62% 11.67% 7.80% 10.42% MSCI AC World Index (Since 7/28/06 ) -0.96% 14.85% 8.12% 9.20% 5.57% 5.99% Returns for less than one year are not annualized. ** Prior to inception of this share class, performance is hypothetical and was calculated from actual returns of the class A shares adjusted for the expenses of the newer share class. Performance data shown represents past performance and is no guarantee of future results. Investment return and principal value will fluctuate so shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than quoted. For performance current to the most recent month end, visit thornburg.com or call 877-215-1330. There is no sales charge for this class of shares. The total annual fund operating expenses are as follows: R4 shares, 1.61%; R5 shares, 1.19%; R6 shares, 1.25%. Thornburg Investment Management and/or Thornburg Securities Corporation have contractually agreed to waive fees and reimburse expenses through at least Feburary 1, 2019, for some of the share classes, resulting in net expense ratios of the following: R4 shares, 1.40%; R5 shares, 0.99%; R6 shares, 0.85%. For more detailed information on fund expenses and waivers/reimbursements please see the fund s prospectus. Hypothetical Growth of $10,000 $40,000 $30,000 R6 Shares $31,827 R5 Shares $31,304 R4 Shares $29,773 MSCI AC World Index $19,710 $20,000 $10,000 $0 Jul-28-06 Dec-08 Dec-10 Dec-12 Dec-14 Mar-18 The Hypothetical Growth of $10,000 graph reflects reinvestment of dividends and capital gains, if any, as well as all fees and expenses. 5

Sector Allocation Information Technology 19.9% Financials 17.5% Industrials 15.8% Consumer Discretionary 10.4% Materials 9.0% Telecommunication Services 7.6% Energy 4.2% Real Estate 3.9% Health Care 2.9% Consumer Staples 2.7% Unassigned 0.6% Cash and Cash Equivalents 5.6% Symbols and Cusips R4 Shares THOVX 885-215-137 R5 Shares THOFX 885-215-129 R6 Shares THOGX 885-216-655 Top Ten Equity Positions (as of 2/28/18 ) Alphabet, Inc. 5.8% Aena S.A. 5.7% Ryanair Holdings plc 5.1% easyjet plc 4.7% T-Mobile US, Inc. 4.6% Facebook, Inc. 4.5% Citigroup, Inc. 4.4% Galaxy Entertainment Group Ltd. 4.1% Baidu, Inc. 3.9% New World Development Co. Ltd. 3.7% Top Ten Countries United States 37.3% Netherlands 12.1% Hong Kong 8.7% United Kingdom 7.9% Spain 6.4% Ireland 5.2% China 4.5% India 4.4% South Korea 4.2% Germany 3.1% Emerging Market Exposure 13.1% Top Ten Industry Groups Transportation 15.8% Software & Services 13.7% Banks 9.2% Materials 9.0% Telecommunication Services 7.6% Technology Hardware & Equipment 6.3% Consumer Services 4.5% Diversifi ed Financials 4.5% Energy 4.2% Real Estate 3.9% Please visit thornburg.com for latest portfolio manager commentary. Important Information Holdings are classified by country of risk as determined by MSCI and Bloomberg. Investments carry risks, including possible loss of principal. Additional risks may be associated with investments outside the United States, especially in emerging markets, including currency fluctuations, illiquidity, volatility, and political and economic risks. Investments in small- and mid-capitalization companies may increase the risk of greater price fluctuations. Investments in the Fund are not FDIC insured, nor are they bank deposits or guaranteed by a bank or any other entity. This class of shares is limited to retirement platforms only. Portfolio attributes and holdings can and do vary. Before investing, carefully consider the Fund s investment goals, risks, charges, and expenses. For a prospectus or summary prospectus containing this and other information, contact your financial advisor or visit thornburg.com. Read it carefully before investing. Glossary Active Share is a measure of the percentage of stock holdings in a manager s portfolio that differ from the benchmark index. Beta is a measure of market-related risk. Less than one means the portfolio is less volatile than the index, while greater than one indicates more volatility than the index. The MSCI All Country (AC) World Index is a market capitalization weighted index that is representative of the market structure of 47 developed and emerging market countries in North and South America, Europe, Africa, the Middle East, and the Pacifi c Rim. The index is calculated with net dividends reinvested in U.S. dollars. Indices do not take into account fees and expenses. Investors cannot make direct investments in an index. Thornburg Securities Corporation, Distributor 2300 North Ridgetop Road Santa Fe, New Mexico 87506 877.215.1330 www.thornburg.com 4/20/18 TH1658 6

Thornburg International Value Fund MARCH 31, 2018 Investment Strategy The Fund invests in a limited number of foreign common stocks selected on a value basis using fundamental research. The portfolio is diversifi ed to include basic value stocks, but also includes stocks of companies with consistent earnings characteristics and those of emerging franchises, when these issues are value priced. Investment Objective The Fund seeks long-term capital appreciation by investing in equity and debt securities of all types. As a secondary consideration, the Fund also seeks some current income. There is no guarantee that the Fund will meet its objectives. Portfolio Managers Lei Wang, CFA Di Zhou, CFA, FRM Supported by the entire Thornburg investment team. Portfolio Baskets Basic Value 53.2% Consistent Earners 28.7% Emerging Franchises 14.1% Cash & Cash Equivalents 4.0% Basic Value: fi nancially sound companies with well-established businesses Consistent Earners: companies which normally exhibit steady earnings growth, cash-fl ow characteristics and/or dividend growth Emerging Franchises: companies in the process of establishing a leading position in a product, service or market Key Portfolio Attributes Portfolio P/E Trailing 12 months* 12.7x Portfolio Price to Cash Flow* 7.2x Portfolio Price to Book Value* 1.4x Median Market Cap* $35.6 B 7-Year Beta (A shares vs. MSCI ACWI ex-u.s.)* 0.92 7-Year Beta (A shares vs. MSCI EAFE)* 0.94 Holdings 46 Fund Assets $5.4 B Active Share (vs. MSCI ACWI ex-u.s.)* 93% Active Share (vs. MSCI EAFE)* 93% Cash & Cash Equivalents 4.0% * Source: FactSet Average Annual Total Returns RETIREMENT SHARE CLASSES Returns for less than one year are not annualized. ** Prior to inception of this share class, performance is hypothetical and was calculated from actual returns of the class A shares adjusted for the expenses of the newer share class. Performance data shown represents past performance and is no guarantee of future results. Investment return and principal value will fluctuate so shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than quoted. For performance current to the most recent month end, visit thornburg.com or call 877-215-1330. There is no sales charge for this class of shares. The total annual fund operating expenses are as follows: R3 shares, 1.60%; R4 shares, 1.42%; R5 shares, 1.18%; R6 shares, 0.82%. Thornburg Investment Management and/or Thornburg Securities Corporation have contractually agreed to waive fees and reimburse expenses through at least February 1, 2019, for some of the share classes, resulting in net expense ratios of the following: R3 shares, 1.45%; R4 shares, 1.25%; R5 shares, 0.99%. For more detailed information on fund expenses and waivers/reimbursements please see the fund s prospectus. $60,000 $50,000 $40,000 Capitalization Exposure Mid 9.2% Large 90.8% YTD 1-YR 3-YR 5-YR 10-YR SINCE A SHARE INCEPTION (5/28/98)** R3 Shares** (Incep: 7/1/03) -2.45% 13.97% 5.31% 5.78% 2.74% 7.58% R4 Shares** (Incep: 2/1/07) -2.39% 14.24% 5.52% 5.99% 2.95% 7.80% R5 Shares** (Incep: 2/1/05) -2.34% 14.50% 5.80% 6.28% 3.22% 8.09% R6 Shares** (Incep: 5/1/12) -2.26% 14.73% 6.03% 6.53% 3.44% 8.33% MSCI EAFE Index (Since 5/28/98) -1.53% 14.80% 5.55% 6.50% 2.74% 4.44% MSCI AC World ex-u.s. Index (Since 5/28/98) -1.18% 16.53% 6.18% 5.89% 2.70% 5.01% Hypothetical Growth of $10,000 R6 Shares $48,940 R5 Shares $46,830 R4 Shares $44,431 R3 Shares $42,623 MSCI AC World ex-u.s. Index $26,864 MSCI EAFE Index $23,791 Small Cap (< $2.5 B); Mid Cap ($2.5 12 B); Large Cap (> $12 B) May not add up to 100% due to rounding. $30,000 $20,000 7 The Hypothetical Growth of $10,000 graph reflects reinvestment of dividends and capital gains, if any, as well as all fees and expenses. $10,000 $0 May-28-98 Dec-01 Dec-04 Dec-07 Dec-10 Dec-13 Mar-18

Sector Allocation Financials 20.6% Energy 12.6% Industrials 12.2% Information Technology 11.8% Consumer Staples 9.4% Health Care 7.9% Utilities 7.0% Consumer Discretionary 6.8% Materials 4.4% Telecommunication Services 2.9% Unassigned 0.2% Cash and Cash Equivalents 4.0% Symbols and Cusips R3 Shares TGVRX 885-215-525 R4 Shares THVRX 885-215-269 R5 Shares TIVRX 885-215-368 R6 Shares TGIRX 885-216-804 Top Ten Equity Positions (as of 2/28/18 ) UniCredit S.p.A. 4.7% Electricite de France SA 3.9% Credit Suisse Group AG 3.9% Commerzbank AG 3.7% Ping An Insurance Group Co. 3.5% Canadian Pacifi c Railway Ltd. 3.5% China Petroleum & Chemical Corp. 3.4% Infi neon Technologies AG 3.1% SAP SE 3.1% Halliburton Co. 2.9% Top Ten Countries China 22.2% France 13.1% Germany 12.5% United Kingdom 8.1% Switzerland 7.7% Japan 6.6% United States 6.4% Netherlands 5.6% Italy 5.0% Spain 4.4% Emerging Market Exposure 25.9% Top Ten Industry Groups Energy 12.6% Banks 10.9% Capital Goods 8.7% Food, Beverage & Tobacco 7.7% Utilities 7.0% Insurance 6.1% Pharma, Biotech & Life Sciences 5.5% Software & Services 4.9% Semiconductors & Equipment 4.9% Materials 4.4% Please visit thornburg.com for latest portfolio manager commentary. Important Information Holdings are classified by country of risk as determined by MSCI and Bloomberg. Investments carry risks, including possible loss of principal. Additional risks may be associated with investments outside the United States, especially in emerging markets, including currency fluctuations, illiquidity, volatility, and political and economic risks. Investments in small- and mid-capitalization companies may increase the risk of greater price fluctuations. Investments in the Fund are not FDIC insured, nor are they bank deposits or guaranteed by a bank or any other entity. This class of shares is limited to retirement platforms only. Portfolio attributes and holdings can and do vary. Before investing, carefully consider the Fund s investment goals, risks, charges, and expenses. For a prospectus or summary prospectus containing this and other information, contact your financial advisor or visit thornburg.com. Read it carefully before investing. Glossary Active Share is a measure of the percentage of stock holdings in a manager s portfolio that differ from the benchmark index. Beta is a measure of market-related risk. Less than one means the portfolio is less volatile than the index, while greater than one indicates more volatility than the index. The MSCI EAFE (Europe, Australasia, Far East) Index is an unmanaged index. It is a generally accepted benchmark for major overseas markets. Index weightings represent the relative capitalizations of the major overseas developed markets on a U.S. dollar adjusted basis. The index is calculated with net dividends reinvested in U.S. dollars. The MSCI All Country (AC) World ex-u.s. Index is a market capitalization weighted index representative of the market structure of 46 developed and emerging market countries in North and South America, Europe, Africa, the Middle East, and the Pacifi c Rim, excluding securities of United States issuers. Beginning in January 2001, the index is calculated with net dividends reinvested in U.S. dollars. Prior data is calculated with gross dividends. Indices do not take into account fees and expenses. Investors cannot make direct investments in an index. 4/20/18 Thornburg Securities Corporation, Distributor 2300 North Ridgetop Road Santa Fe, New Mexico 87506 877.215.1330 www.thornburg.com TH434 8

MARCH 31, 2018 Thornburg International Growth Fund RETIREMENT SHARE CLASSES Investment Strategy The Fund invests in a selection of quality growth stocks, located primarily outside the United States, that management believes will have growing revenues and earnings. The Fund can invest in companies of any size, from large, well-established fi rms to small, emerging growth franchises. Management uses traditional fundamental research to evaluate securities and make buy/ sell decisions. Key Portfolio Attributes Portfolio P/E Trailing 12 months* 20.8x Portfolio Price to Cash Flow* 19.7x Portfolio Price to Book Value* 4.6x Median Market Cap* $14.6 B 7-Yr Beta (A shares vs. MSCI ACWI ex-us Growth)* 0.88 Holdings 55 Fund Assets $1.7 B Active Share (vs. MSCI ACWI ex-us Growth)* 89% Cash & Cash Equivalents 6.8% * Source: FactSet Capitalization Exposure Mid 26.0% Small 7.8% Large 66.3% Small Cap (< $2.5 B); Mid Cap ($2.5 12 B); Large Cap (> $12 B) Charts may not add up to 100% due to rounding. Investment Objective The Fund seeks long-term growth of capital by investing in equity securities selected for their growth potential. There is no guarantee that the Fund will meet its objectives. Portfolio Managers Greg Dunn Sean Koung Sun, CFA Supported by the entire Thornburg investment team. Portfolio Baskets Consistent Growth 29.8% Emerging Growth 31.1% Growth Industry Leaders 32.4% Cash & Cash Equivalents 6.8% Consistent Growth Companies: generally exhibit steady earnings and revenue growth, often with subscription or other recurring revenue profi les. These fi rms tend to buoy the portfolio in weak markets. Emerging Growth Companies: are often addressing a new market or carving out a niche in an existing market. Companies in this basket tend to be smaller, earlier-stage companies. Successful emerging growth companies are often reclassifi ed as their businesses mature. Growth Industry Leaders: often have leadership positions in growing markets. These fi rms tend to be larger, more established, and have dominant market share. Average Annual Total Returns YTD 1-YR 3-YR 5-YR 10-YR SINCE A SHARE INCEPTION (2/1/07)** R3 Shares** (Incep: 2/1/08) 1.80% 23.43% 9.54% 8.18% 7.45% 8.02% R4 Shares** (Incep: 2/1/08) 1.88% 23.58% 9.65% 8.29% 7.56% 8.13% R5 Shares** (Incep: 2/1/08) 1.93% 24.05% 10.10% 8.72% 8.00% 8.57% R6 Shares** (Incep: 2/1/13) 2.01% 24.23% 10.23% 8.83% 8.10% 8.66% MSCI AC World ex-u.s. Growth Index (Since 2/1/07) -0.87% 19.92% 7.28% 6.84% 3.25% 3.66% Returns for less than one year are not annualized. ** Prior to inception of this share class, performance is hypothetical and was calculated from actual returns of the class A shares adjusted for the expenses of the newer share class. Performance data shown represents past performance and is no guarantee of future results. Investment return and principal value will fluctuate so shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than quoted. For performance current to the most recent month end, visit thornburg.com or call 877-215-1330. There is no sales charge for this class of shares. The total annual fund operating expenses are as follows: R3 shares, 2.04%; R4 shares, 1.80%; R5 shares, 1.31%; R6 shares, 1.06%. Thornburg Investment Management and/or Thornburg Securities Corporation have contractually agreed to waive fees and reimburse expenses through at least February 1, 2019, for some of the share classes, resulting in net expense ratios of the following: R3 shares, 1.50%; R4 shares, 1.40%; R5 shares, 0.99%; R6 shares, 0.89%. For more detailed information on fund expenses and waivers/reimbursements please see the fund s prospectus. Hypothetical Growth of $10,000 $30,000 $25,000 $20,000 $15,000 $10,000 $5,000 R6 Shares $25,284 R5 Shares $25,041 R4 Shares $23,938 R3 Shares $23,662 MSCI AC World ex-u.s. Growth Index $14,938 $0 Feb-1-07 Dec-09 Dec-11 Dec-13 Dec-15 Mar-18 The Hypothetical Growth of $10,000 graph reflects reinvestment of dividends and capital gains, if any, as well as all fees and expenses. 9

Sector Allocation Consumer Discretionary 28.4% Information Technology 25.1% Health Care 13.9% Consumer Staples 12.3% Financials 7.1% Industrials 3.9% Energy 1.9% Unassigned 0.6% Cash and Cash Equivalents 6.8% Top Ten Equity Positions (as of 2/28/18) Galaxy Entertainment Group Ltd. 2.9% Bayer AG 2.7% Wirecard AG 2.6% Worldpay, Inc. 2.5% YOOX S.p.A 2.4% adidas AG 2.3% Domino's Pizza Group plc 2.2% Just Eat plc 2.2% Auto Trader Group plc 2.2% Edenred 2.2% Top Ten Industry Groups (as of 3/31/18) Software & Services 25.1% Consumer Services 13.1% Retailing 12.0% Food, Beverage & Tobacco 9.3% Pharma, Biotech & Life Sciences 8.8% Health Care Equipment & Services 5.0% Diversifi ed Financials 5.0% Consumer Durables & Apparel 2.5% Household & Personal Products 2.4% Commercial & Professional Services 2.2% Symbols and Cusips R3 Shares TIGVX 885-215-178 R4 Shares TINVX 885-215-160 R5 Shares TINFX 885-215-152 R6 Shares THGIX 885-216-820 Top Ten Countries (as of 3/31/18) United Kingdom 19.9% Germany 13.5% China 11.1% United States 10.7% Hong Kong 6.7% France 6.6% Japan 4.7% Ireland 4.1% Netherlands 3.3% Mexico 3.0% Emerging Market Exposure 20.7% Please visit thornburg.com for latest portfolio manager commentary. Important Information Holdings are classified by country of risk as determined by MSCI and Bloomberg. Investments carry risks, including possible loss of principal. Additional risks may be associated with investments outside the United States, especially in emerging markets, including currency fluctuations, illiquidity, volatility, and political and economic risks. Investments in small- and mid-capitalization companies may increase the risk of greater price fluctuations. Investments in the Fund are not FDIC insured, nor are they bank deposits or guaranteed by a bank or any other entity. This class of shares is limited to retirement platforms only. Portfolio attributes and holdings can and do vary. Before investing, carefully consider the Fund s investment goals, risks, charges, and expenses. For a prospectus or summary prospectus containing this and other information, contact your financial advisor or visit thornburg.com. Read it carefully before investing. Glossary Active Share is a measure of the percentage of stock holdings in a manager s portfolio that differ from the benchmark index. Beta is a measure of market-related risk. Less than one means the portfolio is less volatile than the index, while greater than one indicates more volatility than the index. The MSCI All Country (AC) World ex-u.s. Growth Index (MSCI ACWI ex-us G) is a market capitalization weighted index that includes growth companies in developed and emerging markets throughout the world, excluding the United States. Indices do not take into account fees and expenses. Investors cannot make direct investments in an index. Thornburg Securities Corporation, Distributor 2300 North Ridgetop Road Santa Fe, New Mexico 87506 877.215.1330 www.thornburg.com 4/20/18 TH1659 10

MARCH 31, 2018 Investment Strategy The Fund invests at least 80% of its assets in equity securities and debt obligations of developing country issuers. A developing country issuer is a company or sovereign entity that is domiciled or otherwise tied economically to one or more developing countries. The Fund portfolio is diversifi ed to include basic value stocks, companies with consistent earnings, and emerging franchises. Investment Objective The Fund seeks long-term capital appreciation. There is no guarantee that the Fund will meet its objectives. Portfolio Managers Ben Kirby, CFA Charles Wilson, PhD Supported by the entire Thornburg investment team. Portfolio Baskets Basic Value43.4% Consistent Earners39.0% Emerging Franchises12.4% Cash & Cash Equivalents5.2% Basic Value: fi nancially sound companies with well-established businesses Consistent Earners: companies which normally exhibit steady earnings growth, cashfl ow characteristics and/or dividend growth Emerging Franchises: companies in the process of establishing a leading position in a product, service or market Thornburg Developing World Fund Key Portfolio Attributes Portfolio P/E Trailing 12 months*10.9x Portfolio Price to Cash Flow*10.1x Portfolio Price to Book Value*2.1x Median Market Cap* $41.4 B 7-Yr Beta (A shares vs. MSCI EM Index)*0.84 Holdings47 Fund Assets $1.1 B Active Share (vs. MSCI EM Index)*77% Cash & Cash Equivalents5.2% * Source: FactSet Average Annual Total Returns RETIREMENT SHARE CLASSES Returns for less than one year are not annualized. ** Prior to inception of this share class, performance is hypothetical and was calculated from actual returns of the class A shares adjusted for the expenses of the newer share class. Performance data shown represents past performance and is no guarantee of future results. Investment return and principal value will fluctuate so shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than quoted. For performance current to the most recent month end, visit thornburg.com or call 877-215-1330. There is no sales charge for this class of shares. The total annual fund operating expenses are as follows: R5 shares, 1.80%; R6 shares, 1.16%. Thornburg Investment Management and/or Thornburg Securities Corporation have contractually agreed to waive fees and reimburse expenses through at least February 1, 2019, for some of the share classes, resulting in net expense ratios of the following: R5 shares, 1.09%; R6 shares, 0.99%. For more detailed information on fund expenses and waivers/reimbursements please see the fund s prospectus. Hypothetical Growth of $10,000 $20,000 $15,000 Capitalization Exposure Small 0.1% Mid 12.9% Large 87.0% Small Cap (< $2.5 B); Mid Cap ($2.5 12 B); Large Cap (> $12 B) Charts may not add up to 100% due to rounding. YTD 1-YR 3-YR 5-YR SINCE A SHARE INCEPTION (12/16/09)** R5 Shares** (Incep: 2/1/13 )-0.56% 24.66% 6.54% 3.88% 7.56% R6 Shares** (Incep: 2/1/13 )-0.51% 24.79% 6.64% 3.98% 7.67% MSCI Emerging Markets Index (Since 12/16/09 )1.42% 24.93% 8.81% 4.99% 4.70% $10,000 $5,000 $0 Dec-16-09 Dec-10 Dec-11 Dec-12 Dec-13 Dec-14 R6 Shares $18,459 R5 Shares $18,299 MSCI EM Index $14,630 Dec-15 Dec-16 Mar-18 The Hypothetical Growth of $10,000 graph reflects reinvestment of dividends and capital gains, if any, as well as all fees and expenses. 11

Sector Allocation Information Technology 29.9% Financials 25.9% Consumer Discretionary 7.7% Consumer Staples 7.4% Energy 6.9% Telecommunication Services 5.6% Real Estate 4.0% Materials 3.7% Health Care 2.3% Industrials 1.3% Cash and Cash Equivalents 5.2% Top Ten Equity Positions (as of 2/28/18 ) Alibaba Group Holding Ltd. 5.9% Tencent Holdings Ltd. 4.7% Industrial and Commercial Bank of China Ltd. 3.2% ICICI Bank Ltd. 3.0% Baidu, Inc. 3.0% Sberbank of Russia PJSC 3.0% Samsung Electronics Co. Ltd. 3.0% Unilever N.V. 2.9% British American Tobacco plc 2.8% HDFC Bank Ltd. 2.7% Top Ten Industry Groups Banks 20.5% Software & Services 17.9% Energy 6.9% Technology Hardware & Equipment 6.3% Consumer Services 5.8% Semiconductors & Equipment 5.6% Telecommunication Services 5.6% Insurance 4.3% Food, Beverage & Tobacco 4.1% Real Estate 4.0% Symbols and Cusips R5 Shares THDRX 885-216-846 R6 Shares TDWRX 885-216-838 Top Ten Countries China 31.8% India 10.9% United Kingdom 8.2% United States 7.2% Brazil 6.3% Mexico 5.5% Russia 5.2% South Korea 4.7% Switzerland 3.9% Hong Kong 3.7% Emerging Market Exposure76.0% Please visit thornburg.com for latest portfolio manager commentary. Important Information Holdings are classified by country of risk as determined by MSCI and Bloomberg. Investments carry risks, including possible loss of principal. Additional risks may be associated with investments outside the United States, especially in emerging markets, including currency fluctuations, illiquidity, volatility, and political and economic risks. Investments in small- and mid-capitalization companies may increase the risk of greater price fluctuations. Investments in the Fund are not FDIC insured, nor are they bank deposits or guaranteed by a bank or any other entity. This class of shares is limited to retirement platforms only. Portfolio attributes and holdings can and do vary. Before investing, carefully consider the Fund s investment goals, risks, charges, and expenses. For a prospectus or summary prospectus containing this and other information, contact your financial advisor or visit thornburg.com. Read it carefully before investing. Glossary Active Share is a measure of the percentage of stock holdings in a manager s portfolio that differ from the benchmark index. Beta is a measure of market-related risk. Less than one means the portfolio is less volatile than the index, while greater than one indicates more volatility than the index. The MSCI Emerging Markets Index is a free fl oat-adjusted market capitalization index that is designed to measure equity market performance of emerging markets. The MSCI Emerging Markets Index consists of the following 23 emerging market country indices: Brazil, Chile, China, Colombia, Czech Republic, Egypt, Greece, Hungary, India, Indonesia, Korea, Malaysia, Mexico, Peru, Philippines, Poland, Qatar, Russia, South Africa, Taiwan, Thailand, Turkey, and United Arab Emirates. Indices do not take into account fees and expenses. Investors cannot make direct investments in an index. Thornburg Securities Corporation, Distributor 2300 North Ridgetop Road Santa Fe, New Mexico 87506 877.215.1330 www.thornburg.com 4/20/18 TH2717 12

MARCH 31, 2018 Investment Strategy The Fund invests in a limited number of common stocks selected on a value basis using fundamental research. The portfolio is diversifi ed to include basic value stocks, but also includes stocks of companies with consistent earnings characteristics and those of emerging franchises, when these issues are value priced. Investment Objective The Fund seeks long-term capital appreciation by investing in equity and debt securities of all types. As a secondary consideration the Fund also seeks some current income. There is no guarantee that the Fund will meet its objectives. Portfolio Managers Connor Browne, CFA Robert MacDonald, CFA Supported by the entire Thornburg investment team. Portfolio Baskets Basic Value 39.0% Consistent Earners 46.3% Emerging Franchises 9.0% Cash & Cash Equivalents 5.7% Basic Value: fi nancially sound companies with well-established businesses Consistent Earners: companies which normally exhibit steady earnings growth, cashfl ow characteristics and/or dividend growth Emerging Franchises: companies in the process of establishing a leading position in a product, service or market Portfolio Composition Domestic Equity 82.6% Foreign Equity 11.8% Cash & Cash Equivalents 5.7% Thornburg Value Fund Key Portfolio Attributes Portfolio P/E Trailing 12 months* 16.3x Portfolio Price to Cash Flow* 9.5x Portfolio Price to Book Value* 2.1x Median Market Cap* $12.7 B 7-Yr Beta (A shares vs. S&P 500)* 1.15 Holdings 46 Fund Assets $962 M Active Share (vs. S&P 500)* 88% Cash & Cash Equivalents 5.7% * Source: FactSet Average Annual Total Returns RETIREMENT SHARE CLASSES Returns for less than one year are not annualized. ** Prior to inception of this share class, performance is hypothetical and was calculated from actual returns of the class A shares adjusted for the expenses of the newer share class. Performance data shown represents past performance and is no guarantee of future results. Investment return and principal value will fluctuate so shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than quoted. For performance current to the most recent month end, visit thornburg.com or call 877-215-1330. There is no sales charge for this class of shares. The total annual fund operating expenses are as follows: R3 shares, 1.78%; R4 shares, 1.74%; R5 shares, 1.45%. Thornburg Investment Management and/or Thornburg Securities Corporation have contractually agreed to waive fees and reimburse expenses through at least February 1, 2019, for some of the share classes, resulting in net expense ratios of the following: R3 shares, 1.35%; R4 shares, 1.25%; R5 shares, 0.99%. For more detailed information on fund expenses and waivers/reimbursements please see the fund s prospectus. Hypothetical Growth of $10,000 $100,000 $80,000 $60,000 $40,000 $20,000 $0 Oct-2-95 Dec-97 Dec-99 Dec-01 Dec-03 Dec-05 Capitalization Exposure Mid 30.3% Dec-07 Dec-09 Small 10.4% Dec-11 Dec-13 Large 59.3% Small Cap (< $2.5 B); Mid Cap ($2.5 12 B); Large Cap (> $12 B) Charts may not add up to 100% due to rounding. YTD 1-YR 3-YR 5-YR 10-YR SINCE A SHARE INCEPTION (10/2/95)** R3 Shares** (Incep: 7/1/03) -1.77% 12.40% 8.91% 13.39% 7.62% 9.89% R4 Shares** (Incep: 2/1/07) -1.75% 12.52% 9.02% 13.50% 7.74% 10.04% R5 Shares** (Incep: 2/1/05) -1.69% 12.80% 9.31% 13.79% 8.02% 10.33% S&P 500 Index (Since 10/2/95) -0.76% 13.99% 10.78% 13.31% 9.49% 9.01% R5 Shares $91,489 R4 Shares $86,178 R3 Shares $83,551 S&P 500 Index $69,565 Dec-15 Mar-18 The Hypothetical Growth of $10,000 graph reflects reinvestment of dividends and capital gains, if any, as well as all fees and expenses. 13

Sector Allocation Information Technology 18.6% Financials 17.4% Health Care 15.8% Consumer Discretionary 14.1% Consumer Staples 9.3% Energy 5.9% Industrials 4.4% Materials 4.1% Telecommunication Services 2.6% Utilities 1.3% Real Estate 0.8% Cash and Cash Equivalents 5.7% Symbols and Cusips R3 Shares TVRFX 885-215-533 R4 Shares TVIRX 885-215-277 R5 Shares TVRRX 885-215-376 Top Ten Equity Positions (as of 2/28/18) JPMorgan Chase & Co. 4.7% Thermo Fisher Scientifi c, Inc. 4.7% Gilead Sciences, Inc. 4.5% US Foods Holding Corp. 4.2% Alphabet, Inc. 3.8% Citigroup, Inc. 3.3% Assured Guaranty Ltd. 3.2% RPC Group plc 3.0% Medtronic plc 3.0% Walmart, Inc. 2.9% Top Ten Industry Groups (as of 3/31/18) Pharma, Biotech & Life Sciences 11.7% Technology Hardware & Equipment 9.6% Software & Services 9.0% Banks 8.1% Food & Staples Retailing 6.7% Diversifi ed Financials 5.9% Energy 5.9% Consumer Services 5.0% Consumer Durables & Apparel 4.9% Retailing 4.2% Please visit thornburg.com for latest portfolio manager commentary. Important Information Investments carry risks, including possible loss of principal. Additional risks may be associated with investments outside the United States, especially in emerging markets, including currency fluctuations, illiquidity, volatility, and political and economic risks. Investments in small- and mid-capitalization companies may increase the risk of greater price fluctuations. Investments in the Fund are not FDIC insured, nor are they bank deposits or guaranteed by a bank or any other entity. This class of shares is limited to retirement platforms only. Portfolio attributes and holdings can and do vary. Before investing, carefully consider the Fund s investment goals, risks, charges, and expenses. For a prospectus or summary prospectus containing this and other information, contact your financial advisor or visit thornburg.com. Read it carefully before investing. Glossary Active Share is a measure of the percentage of stock holdings in a manager s portfolio that differ from the benchmark index. Beta is a measure of market-related risk. Less than one means the portfolio is less volatile than the index, while greater than one indicates more volatility than the index. The S&P 500 Index is an unmanaged broad measure of the U.S. stock market. Indices do not take into account fees and expenses. Investors cannot make direct investments in an index. Thornburg Securities Corporation, Distributor 2300 North Ridgetop Road Santa Fe, New Mexico 87506 877.215.1330 www.thornburg.com 4/20/18 TH433 14

Thornburg Core Growth Fund MARCH 31, 2018 RETIREMENT SHARE CLASSES Investment Strategy Key Portfolio Attributes Capitalization Exposure The Fund invests in a selection of quality growth stocks that management believes will have growing revenues and earnings. The Fund can invest in companies of any size, from large, well-established fi rms to small, emerging growth franchises. Management uses traditional fundamental research to evaluate securities and make buy/sell decisions. Portfolio P/E Trailing 12 months* 23.7x Portfolio Price to Cash Flow* 17.5x Portfolio Price to Book Value* 4.8x Median Market Cap* $24.8 B 7-Yr Beta (A shares vs. Russell 3000 Growth)* 1.12 Holdings 45 Fund Assets $661 M Active Share (vs. Russell 3000 Growth)* 81% Cash & Cash Equivalents 10.5% Mid 22.5% Small 2.8% Large 74.7% Investment Objective * Source: FactSet Small Cap (< $2.5 B); Mid Cap ($2.5 12 B); Large Cap (> $12 B) Charts may not add up to 100% due to rounding. The Fund seeks long-term growth of capital by investing in equity securities selected for their growth potential. There is no guarantee that the Fund will meet its objectives. Portfolio Manager Greg Dunn Supported by the entire Thornburg investment team. Portfolio Baskets Growth Industry Leaders 36.7% Consistent Growth 23.7% Emerging Growth 29.1% Cash & Cash Equivalents 10.5% Growth Industry Leaders: often have leadership positions in growing markets. These fi rms tend to be larger, more established, and have dominant market share. Consistent Growth Companies: generally exhibit steady earnings and revenue growth, often with subscription or other recurring revenue profi les. These fi rms tend to buoy the portfolio in weak markets. Emerging Growth Companies: are often addressing a new market or carving out a niche in an existing market. Companies in this basket tend to be smaller, earlier-stage companies. Successful emerging growth companies are often reclassifi ed as their businesses mature. Average Annual Total Returns YTD 1-YR 3-YR 5-YR 10-YR SINCE A SHARE INCEPTION (12/27/00)** R3 Shares** (Incep: 7/1/03) 5.91% 20.20% 8.24% 10.98% 8.20% 6.68% R4 Shares** (Incep: 2/1/07) 5.95% 20.33% 8.35% 11.09% 8.31% 6.81% R5 Shares** (Incep: 10/3/05) 6.00% 20.77% 8.78% 11.54% 8.74% 7.24% Russell 3000 Growth Index (Since 12/27/00) 1.48% 21.06% 12.57% 15.32% 11.31% 5.87% Returns for less than one year are not annualized. ** Prior to inception of this share class, performance is hypothetical and was calculated from actual returns of the class A shares adjusted for the expenses of the newer share class. Performance data shown represents past performance and is no guarantee of future results. Investment return and principal value will fluctuate so shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than quoted. For performance current to the most recent month end, visit thornburg.com or call 877-215-1330. There is no sales charge for this class of shares. The total annual fund operating expenses are as follows: R3 shares, 1.80%; R4 shares, 1.96%; R5 shares, 1.37%. Thornburg Investment Management and/or Thornburg Securities Corporation have contractually agreed to waive fees and reimburse expenses through at least February 1, 2019, for some of the share classes, resulting in net expense ratios of the following: R3 shares, 1.50%; R4 shares, 1.40%; R5 shares, 0.99%. For more detailed information on fund expenses and waivers/reimbursements please see the fund s prospectus. Hypothetical Growth of $10,000 $40,000 $30,000 $20,000 $10,000 R5 Shares $33,418 R4 Shares $31,178 R3 Shares $30,524 Russell 3000 Growth Index $26,765 $0 Dec-27-00 Dec-04 Dec-07 Dec-10 Dec-13 Mar-18 The Hypothetical Growth of $10,000 graph reflects reinvestment of dividends and capital gains, if any, as well as all fees and expenses. 15

Sector Allocation Information Technology 36.1% Consumer Discretionary 17.3% Health Care 13.6% Financials 9.1% Consumer Staples 6.6% Energy 3.5% Materials 3.4% Cash and Cash Equivalents 10.5% Symbols and Cusips R3 Shares THCRX 885-215-517 R4 Shares TCGRX 885-215-251 R5 Shares THGRX 885-215-350 Top Ten Equity Positions (as of 2/28/18) Visa, Inc. 4.5% FleetCor Technologies, Inc. 3.7% Amazon.com, Inc. 3.4% Las Vegas Sands Corp. 3.2% Alphabet, Inc. 3.1% Facebook, Inc. 3.1% SVB Financial Group 2.7% ServiceNow, Inc. 2.5% DexCom, Inc. 2.4% Zillow Group, Inc. 2.4% Top Ten Industry Groups (as of 3/31/18) Software & Services 32.5% Retailing 10.5% Health Care Equipment & Services 7.4% Pharma, Biotech & Life Sciences 6.2% Banks 4.9% Food, Beverage & Tobacco 4.5% Diversifi ed Financials 4.2% Media 3.6% Technology Hardware & Equipment 3.6% Energy 3.5% Please visit thornburg.com for latest portfolio manager commentary. Important Information Investments carry risks, including possible loss of principal. Additional risks may be associated with investments outside the United States, especially in emerging markets, including currency fluctuations, illiquidity, volatility, and political and economic risks. Investments in small- and mid-capitalization companies may increase the risk of greater price fluctuations. Investments in the Fund are not FDIC insured, nor are they bank deposits or guaranteed by a bank or any other entity. This class of shares is limited to retirement platforms only. Portfolio attributes and holdings can and do vary. Before investing, carefully consider the Fund s investment goals, risks, charges, and expenses. For a prospectus or summary prospectus containing this and other information, contact your financial advisor or visit thornburg.com. Read it carefully before investing. Glossary Active Share is a measure of the percentage of stock holdings in a manager s portfolio that differ from the benchmark index. Beta is a measure of market-related risk. Less than one means the portfolio is less volatile than the index, while greater than one indicates more volatility than the index. The Russell 3000 Growth Index is an unmanaged index comprised of those Russell 3000 companies with higher price-to-book ratios and higher forecasted growth values. The stocks in this index are also members of either the Russell 1000 Growth or the Russell 2000 Growth indices. Source: Frank Russell Company Indices do not take into account fees and expenses. Investors cannot make direct investments in an index. Thornburg Securities Corporation, Distributor 2300 North Ridgetop Road Santa Fe, New Mexico 87506 877.215.1330 www.thornburg.com 4/20/18 TH435 16

MARCH 31, 2018 Investment Strategy The Fund is an actively managed, laddered portfolio of short/intermediate-term obligations issued by the U.S. Government, its agencies or instrumentalities with an average maturity of less than fi ve years. Laddering involves building a portfolio of bonds with staggered maturities so that a portion of the portfolio matures each year; cash from maturing bonds is invested in bonds with longer maturities at the far end of the ladder. The strategy is a good compromise for managing different types of risk. Portfolio Managers Jason Brady, CFA Lon Erickson, CFA Jeff Klingelhofer, CFA Supported by the entire Thornburg investment team. Symbols and Cusips R4 Shares LTUGX 885-216-747 R5 Shares LTGRX 885-216-861 Thornburg Limited Term U.S. Government Fund Key Portfolio Attributes Fund Assets $265 M Number of Bonds 156 Average Maturity 3.6 Yrs Effective Duration 2.8 Yrs Portfolio Composition Mortgage Pass Through 23.9% Treasury 23.7% Collateralized Mortgage Obligation 16.4% Comm. Mortgage-backed Securities 12.4% Government Agency 11.8% Asset-backed Securities 5.0% Cash & Cash Equivalents 6.8% Average Annual Total Returns RETIREMENT SHARE CLASSES Current Portfolio Ladder % of portfolio maturing in each year (The percentages can and do vary over time.) Cash includes cash equivalents. Yr 5 Yr 4 Yr 3 Yr 2 Yr 1 Cash 7% 9% 4% 19% 22% 19% 4% 4% 8% 2% 1% Charts may not add up to 100% due to rounding. Returns for less than one year are not annualized. * Prior to inception of this share class, performance is hypothetical and was calculated from actual returns of the class A shares adjusted for the expenses of the newer share class. Performance data shown represents past performance and is no guarantee of future results. Investment return and principal value will fluctuate so shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than quoted. For performance current to the most recent month end, visit thornburg.com or call 877-215-1330. There is no sales charge for this class of shares. The total annual fund operating expenses are as follows: R4 shares, 1.91%; R5 shares 1.24%. Thornburg Investment Management and/or Thornburg Securities Corporation have contractually agreed to waive fees and reimburse expenses through at least February 1, 2019, for some of the share classes, resulting in net expense ratios of the following: R4 shares, 0.99%; R5 shares, 0.67%. For more detailed information on fund expenses and waivers/reimbursements please see the fund s prospectus. Yr 6 Yr 7 YTD 1-YR 3-YR 5-YR 10-YR Yr 8 Yr 10+ Yr 9 SINCE A SHARE INCEPTION (11/16/87)* R4 Shares* (Incep: 2/1/14) -0.56% -0.21% 0.13% 0.31% 1.79% 4.65% R5 Shares* (Incep: 5/1/12) -0.54% 0.14% 0.48% 0.65% 2.13% 4.97% Please visit thornburg.com for latest portfolio manager commentary. Important Information Investments carry risks, including possible loss of principal. Portfolios investing in bonds have the same interest rate, inflation, and credit risks that are associated with the underlying bonds. The value of bonds will fluctuate relative to changes in interest rates, decreasing when interest rates rise. Unlike bonds, bond funds have ongoing fees and expenses. Investments in mortgage-backed securities (MBS) may bear additional risk. Investments in the Funds are not FDIC insured, nor are they bank deposits or guaranteed by a bank or any other entity. This class of shares is limited to retirement platforms only. Effective Duration is a bond s sensitivity to interest rates, incorporating the embedded option features, such as call provisions. Bonds with longer durations experience greater price volatility than bonds with shorter durations. Before investing, carefully consider the Fund s investment goals, risks, charges, and expenses. For a prospectus or summary prospectus containing this and other information, contact your financial advisor or visit thornburg.com. Read it carefully before investing. Thornburg Securities Corporation, Distributor 2300 North Ridgetop Road Santa Fe, New Mexico 87506 877.215.1330 www.thornburg.com 4/20/18 TH436 17