American Century International Growth Investor Class (TWIEX) is a mutual fund offered by American Century Investments that seeks long-term capital growth by investing primarily in common stocks of companies located in developed markets outside the United States; the fund emphasizes issuers demonstrating strong growth potential, attractive valuations, and competitive advantages, with a portfolio typically comprising large- and mid-cap equities across diverse sectors such as information technology, consumer discretionary, industrials, health care, and financials. Core offerings include multiple share classes including Investor Class (TWIEX), R6 Class (ACPLX), and others, with services encompassing automatic investment plans, exchange privileges among American Century funds, and retirement account integration; the fund maintains a focus on non-U.S. equities from Europe, Asia-Pacific, and other developed regions, targeting institutional and retail investors seeking international diversification. American Century Investments, founded in 1958 and headquartered in Kansas City, Missouri, manages the fund as part of its broader equity platform serving individual investors, financial advisors, and institutions globally. In recent developments, the fund underwent a portfolio manager transition in 2023 with the addition of experienced analysts to enhance international growth expertise; American Century announced strategic enhancements to its sustainable investing framework in 2024, integrating ESG factors into select growth strategies including international mandates without altering TWIEX's core objectives; the firm also expanded distribution partnerships with major platforms like Schwab and Fidelity in late 2024 to broaden access amid rising demand for active international equity exposure.