The Pimco Total Return Fund, the world's largest bond fund run by Bill Gross, fell about 1 percent in December, beating just 6 percent of peers, preliminary data from Morningstar showed on Thursday.
The fund, which has roughly $244 billion in assets, fell 1.92 percent for the year, beating 41 percent of peers, the data showed. The fund is the flagship of Pacific Investment Management, which had $1.97 trillion in assets as of Sept. 30, according to the firm's website.
The Pimco Total Return Exchange-Traded Fund, an actively-managed ETF designed to mimic the strategy of the flagship mutual fund, fell 0.85 percent for the month, putting it in the lowest percentile rank for its category for the month.
(Read more: Gross: Fed will keep rates low until 2016)
Investors pulled $115.8 million from the ETF in December, marking its eighth straight month of withdrawals, Morningstar data showed. The ETF has about $3.5 billion in assets.
Jeffrey Gundlach's DoubleLine Total Return Bond Fund , a competitor to the Pimco fund, fell 0.7 percent in December, beating 19 percent of peers. The fund had outflows of $2.08 billion in December, Reuters reported on Wednesday.