The $22.2 billion Fidelity Total Bond Fund, recipient of $4.3 billion in inflows, is down 0.3 percent in 2015. The Fidelity fund was hurt by investments in high-yield bonds, which lost ground mostly in the second half of the year, said Sophie Launay, a Fidelity spokeswoman.

Fidelity’s Bet

“Recently the fund’s performance has been affected by an overweight in non-investment grade positions,” Launay said in an e-mail. “The portfolio managers have looked to take advantage of attractively priced securities in high yield, leverage loans and emerging market debt that they believe could benefit the fund and its shareholders over the long term.”

Pimco Total Return also beat the $149.7 billion Vanguard Total Bond Market Index Fund, which attracted $10.5 billion through Nov. 30, including assets in an exchange-traded fund share class, and now ranks as the largest bond fund. The Vanguard fund, which tracks the broader market, is up 0.6 percent this year.

The $22.5 billion Vanguard Intermediate-Term Bond Index Fund, which tracks an index of five- to 10-year U.S. government and corporate debt, did better than Pimco Total Return in 2015 and the last three and five years, and took in about $5 billion in this year’s first 11 months. One edge for the Vanguard indexed funds is lower fees than actively managed funds like Pimco’s, which can affect returns over time.

‘Difficult Situation’

“Our philosophy is long term,” said David Hoffman, a spokesman for Vanguard. “When we talk about long term, we talk about three, five, 10 years out. A single year, that’s not long term.”

Carl Eichstaedt, who worked at Pimco in the 1990s and who now helps run the $15.3 billion Western Asset Core Plus Bond Fund, said Total Return’s managers deserve respect for generating relatively high returns while experiencing heavy redemptions.

“I have to give them credit, because it’s a difficult situation to be in,” Eichstaedt said in an interview. “They couldn’t afford another mistake.”

Eichstaedt’s fund ranks sixth in inflows at $2.2 billion. It returned 1.5 percent by avoiding energy, while investing in mortgage-backed securities and higher-yielding corporate credit in safer sectors, such as financials.