Thornburg International Growth Fund | A C I

FUND SUMMARY

International Growth Fund

Investment Goal

The Fund seeks long-term growth of capital by investing in equity securities selected for their growth potential.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for discounts from the sales charges applicable to Class A shares if you or other qualifying account holders invest, or agree to invest in the future, at least $50,000 in the Thornburg Funds. More information about these and other discounts is available from your financial professional and in “Opening Your Account – Buying Fund Shares” on page 82 of this Prospectus.

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Thornburg International Growth Fund A C I	Class A		Class C		Class I
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	4.50%		none		none
Maximum Deferred Sales Charge (Load) (as a percentage of redemption proceeds or original purchase price, whichever is lower)	none	[1]	1.00%	[2]	none

Annual Fund Operating Expenses
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Thornburg International Growth Fund A C I	Class A	Class C	Class I
Management Fees	0.88%	0.88%	0.88%
Distribution and Service (12b-1) Fees	0.25%	1.00%	none
Other Expenses	0.20%	0.21%	0.10%
Total Annual Fund Operating Expenses	1.33%	2.09%	0.98%

Example.

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year, dividends and distributions are reinvested, and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example Thornburg International Growth Fund A C I (USD $)	1 Year	3 Years	5 Years	10 Years
Class A Shares	579	852	1,146	1,979
Class C Shares	312	655	1,124	2,421
Class I Shares	100	312	542	1,201

You would pay the following expenses if you did not redeem your Class C shares:

Expense Example, No Redemption (USD $)	1 Year	3 Years	5 Years	10 Years
Thornburg International Growth Fund A C I Class C Shares	212	655	1,124	2,421

Portfolio Turnover.

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over”) its portfolio. A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 106.18% of the average value of its portfolio.

Principal Investment Strategies

The Fund expects to invest primarily in equity securities from issuers around the world (primarily common stocks) selected for their growth potential and, under normal market conditions, invests at least 75% of its assets in foreign securities or depository receipts of foreign securities. However, the Fund may own a variety of securities, including domestic equity securities and partnership interests. The Fund may invest in developing countries and in smaller companies with market capitalizations of less than $500 million.

The Fund’s investment advisor, Thornburg Investment Management, Inc. (“Thornburg”) intends to invest in companies that it believes will have growing revenues and earnings. The Fund can invest in companies of any size, from larger, well-established companies to smaller, emerging growth companies.

Thornburg primarily uses individual issuer and industry analysis to make investment decisions. Among the specific factors considered by Thornburg in identifying securities for inclusion in the Fund are:

■	earnings growth potential	■	price/revenue ratio
■	business model	■	PE/growth rate ratio
■	industry growth potential	■	price/cash flow ratio
■	industry leadership	■	enterprise value/EBITDA (earnings before interest, taxes, depreciation and amortization) ratio
■	asset appreciation potential	■	management strength
■	potential size of business	■	debt/capital ratio
■	value based on earnings growth discount model
■	price/earnings ratio

The Fund typically makes equity investments in the following three types of companies:

Growth Industry Leaders: Companies in this category often have leadership positions in growing markets. In some cases these companies may have dominant market share. These companies tend to be larger and more established.

Consistent Growers: Companies in this category generally exhibit steady earnings or revenue growth, or both. These companies often have subscription or other recurring revenue profiles. Given their business models, these companies may outperform in weak markets.

Emerging Growth Companies: Companies often addressing a new market or carving out a niche in an existing market. Companies in this category may experience rapid growth, and tend to be smaller, earlier stage companies. Thornburg expects that companies in this category should generate high returns over time, but with higher volatility.

In conjunction with individual issuer analysis, Thornburg may identify economic sectors it expects to experience growth. At times this approach may produce a focus on certain industries, such as technology, financial services, health-care or biotechnology. The exposure to particular economic sectors or industries likely will vary over time. Investment decisions are also based on domestic and international economic developments, outlooks for securities markets, interest rates and inflation, and the supply and demand for debt and equity securities.

Debt obligations, usually with associated equity features, occasionally will be considered for investment when Thornburg believes them to be more attractive than equity alternatives. The Fund may purchase debt obligations of any maturity and of any credit quality, including “high yield” or “junk” bonds. There is no minimum credit quality or rating of debt obligation the Fund may purchase.

Principal Investment Risks

An investment in the Fund is not a deposit in any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Accordingly, the loss of money is a risk of investing in the Fund. The value of the Fund’s shares varies from day to day and over time, and when you sell your shares they may be worth less than what you paid for them. The following is a summary of the principal risks of investing in the Fund.

Management Risk – The Fund is an actively managed portfolio, and the value of the Fund may be reduced if Thornburg pursues unsuccessful investments or fails to correctly identify risks affecting the broad economy or specific issuers in which the Fund invests.

Market and Economic Risk – The value of the Fund’s investments may decline and its share value may be reduced due to changes in general economic and market conditions. The value of a security may change in response to developments affecting entire economies, markets or industries, including changes in interest rates, political and legal developments, and general market volatility.

Risks Affecting Specific Issuers – The value of an equity security or debt obligation may decline in response to developments affecting the specific issuer of the security or obligation, even if the overall industry or economy is unaffected. These developments may include a variety of factors, including but not limited to management issues or other corporate disruption, a decline in revenues or profitability, an increase in costs, or an adverse effect on the issuer’s competitive position.

Foreign Investment Risk – Investments in securities of foreign issuers may involve risks including adverse fluctuations in currency exchange rates, political instability, confiscations, taxes or restrictions on currency exchange, difficulty in selling foreign investments, and reduced legal protection.

Developing Country Risk – The risks which may affect investments in foreign issuers (see “Foreign Investment Risk,” above) may be more pronounced for investments in developing countries because the economies of those countries are usually less diversified, communications, transportation and economic infrastructures are less developed, and developing countries ordinarily have less established legal, political, business and social frameworks. At times the prices of equity securities or debt obligations of a developing country issuer may be extremely volatile. An issuer domiciled in a developed country may be similarly affected by these developing country risks to the extent that the issuer conducts a significant percentage of its business in developing countries.

Small and Mid-Cap Company Risk – Investments in small-capitalization companies and mid-capitalization companies may involve additional risks, which may be relatively higher with smaller companies. These additional risks may result from limited product lines, more limited access to markets and financial resources, greater vulnerability to competition and changes in markets, lack of management depth, increased volatility in share price, and possible difficulties in valuing or selling these investments.

Credit Risk – If debt obligations held by the Fund are downgraded by ratings agencies or go into default, or if management action, legislation or other government action reduces the ability of issuers to pay principal and interest when due, the value of those debt obligations may decline and the Fund’s share value and any dividends paid by the Fund may be reduced. Because the ability of an issuer of a lower-rated or unrated debt obligation (including particularly “junk” or “high yield” bonds) to pay principal and interest when due is typically less certain than for an issuer of a higher-rated debt obligation, lower-rated and unrated debt obligations are generally more vulnerable than higher-rated debt obligations to default, to ratings downgrades, and to liquidity risk.

Interest Rate Risk – When interest rates increase, the value of the Fund’s investments in debt obligations may decline and the Fund’s share value may be reduced. This effect is typically more pronounced for intermediate and longer-term debt obligations. Decreases in market interest rates may result in prepayments of debt obligations the Fund acquires, requiring the Fund to reinvest at lower interest rates.

Liquidity Risk – Due to a lack of demand in the marketplace or other factors, the Fund may not be able to sell some or all of the investments promptly, or may only be able to sell investments at less than desired prices. This risk may be more pronounced for the Fund’s investments in developing countries.

Additional information about Fund investments, investment strategies, and risks of investing in the Fund appears below beginning on page 74.

Past Performance of the Fund

The following information provides some indication of the risks of investing in International Growth Fund by showing how the Fund’s investment results vary from year to year. The bar chart shows how the annual total return for Class A shares has been different in each full year shown. The average annual total return figures compare Class A, Class C and Class I share performance to the Morgan Stanley Capital International (MSCI) All Country (AC) World ex-U.S. Growth Index, a market capitalization weighted index which includes growth companies in developed and emerging markets throughout the world, excluding the United States. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. The performance information shown below is as of the calendar year ended December 31, 2014. Updated performance information may be obtained on the Thornburg website at www.thornburg.com or by calling 1-800-847-0200.

Annual Total Returns – Class A Shares

Highest quarterly results for time period shown: 28.24%
(quarter ended 6-30-09).

Lowest quarterly results for time period shown: -25.74%
(quarter ended 12-31-08).

The sales charge for Class A shares is not reflected in the returns shown on the bar chart, and the returns would be less if the charge was taken into account.

Average Annual Total Returns (periods ended 12-31-14)

Average Annual Total Returns Thornburg International Growth Fund A C I	1 Year	5 Years	Since Inception	Inception Date
Class A Shares	(16.39%)	11.41%	6.44%	Feb. 01, 2007
Class A Shares Return After Taxes on Distributions	(17.40%)	10.93%	5.93%	Feb. 01, 2007
Class A Shares Return After Taxes on Distributions and Sale of Fund Shares	(8.42%)	9.06%	4.99%	Feb. 01, 2007
Class A Shares MSCI AC World ex-U.S. Growth Index (reflects no deduction for fees, expenses, or taxes)	(2.65%)	5.19%	1.83%	Feb. 01, 2007
Class C Shares	(13.94%)	11.58%	6.32%	Feb. 01, 2007
Class C Shares MSCI AC World ex-U.S. Growth Index (reflects no deduction for fees, expenses, or taxes)	(2.65%)	5.19%	1.83%	Feb. 01, 2007
Class I Shares	(12.15%)	12.97%	7.62%	Feb. 01, 2007
Class I Shares MSCI AC World ex-U.S. Growth Index (reflects no deduction for fees, expenses, or taxes)	(2.65%)	5.19%	1.83%	Feb. 01, 2007

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect state or local income taxes. Actual after-tax returns depend on an investor’s own tax situation and may differ from the returns shown, and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The after-tax returns shown relate only to Class A shares, and after-tax returns will vary for Class C and Class I shares because the returns of the classes are different.

[1] A 1.00% contingent deferred sales charge (CDSC) is imposed on redemptions of any part or all of a purchase of $1 million or more within 12 months of purchase.

[2] Imposed only on redemptions of Class C shares within 12 months of purchase.