The Schwab U.S. Aggregate Bond Index Fund (SWAGX) is a mutual fund that seeks to track the performance of the U.S. Aggregate Bond Index. This index is a broad measure of the U.S. investment-grade bond market, including government, corporate, and mortgage-backed securities. SWAGX provides investors with a diversified portfolio of high-quality bonds, making it a suitable option for those seeking a low-risk investment with potential for steady income.