Guess who's picking up the cash that's flowed out of Pimco

The nightmare that was 2013 for Pacific Investment Management Co. left the door open for other bond fund managers to win over fixed-income investors — and BlackRock Inc. and The Goldman Sachs Group Inc. barged right in.

Last year, investors pulled more than $20 billion net from Pimco, the world's largest bond fund manager, including an eye-popping $41 billion from its flagship Pimco Total Return Fund (PTTAX), as performance suffered from bad bets on how tapering would play out. By the end of October, the $287 billion Vanguard Total Stock Market Index Fund (VTSMX) had toppled the Total Return Fund as the largest mutual fund.

The $237 billion Pimco Total Return Fund lost 2.3% in 2013, which was worse than the benchmark Barclays U.S. Aggregate Bond Index's 2% drop, and worse than 74% of its peers in the intermediate-term bond fund category, according to Morningstar Inc.

The rest of Pimco's bond funds didn't fare much better. Pimco mutual funds with more than $10 billion in assets on average trailed about two-thirds of peers in 2013, according to data compiled by Bloomberg.

BlackRock and Goldman benefited from the outperformance of their nontraditional bond funds, which are not tied to any index and free to invest anywhere across the fixed-income spectrum.

“Advisers are going from your standard bond choice into something that is less constrained by convention,” said Jeff Tjornehoj, a senior research analyst at Lipper Inc.

The $11 billion BlackRock Strategic Income Fund (BASIX) had a 3% return in 2013 and the $14.7 billion Goldman Sachs Strategic Income Fund (GSZAX) a 6% return.

Those two funds took in a combined $16 billion through the first 11 months of the year.

Pimco also offers a nontraditional bond fund, but it performed even worse than the Total Return Fund. The $26.8 billion Pimco Unconstrained Bond Fund (PUBAX) lost 2.6% last year.

Thanks primarily to their unconstrained funds, BlackRock and Goldman were the only two mutual fund companies to attract more than $10 billion of net inflows into their bond funds through the first 11 months of the year, according to Morningstar. BlackRock took in $11.5 billion and Goldman took in $10.4 billion.

Overall, investors pulled out a record $86 billion from bond funds in 2013, according to research firm TrimTabs.

The trend isn't expected to reverse itself anytime soon.

“Flipping the calendar doesn't change people's habits,” Mr. Tjornehoj said.