VFSIX is a mutual fund offered by Vanguard that focuses on short-term investment grade bonds. It is designed for institutional investors and aims to provide a stable and low-risk option for those seeking short-term fixed income investments. The fund primarily invests in high-quality corporate bonds with short maturities, making it a suitable choice for investors looking for a conservative approach to fixed income investing. With a low expense ratio and a track record of consistent returns, VFSIX is a reliable option for those looking to diversify their portfolio with short-term investment grade bonds.