The PIMCO Total Return Fund has lost its crown as the world's biggest mutual fund to Vanguard's Total Stock Market Index Fund in another sign that investors are rapidly rotating from bonds into stocks. Gross's flagship fund fell to $248bn in assets at the end of October, after another month of withdrawals. Investors asked for $4.4bn back last month, taking the outflows for 2013 so far to $33.2bn. The possibility of rising interest rates mean core bond funds are at risk of falling in value, meaning investors are seeking out equity funds or smaller, flexible fixed income funds that can invest more in credit instruments and emerging markets debt.