Boston-based Fidelity owned about 4 percent of Buffalo Wild Wings' stock at the end of March, down from 15 percent three months earlier, according to a regulatory filing made late Thursday.

Fidelity portfolio managers Steven Wymer and Gavin Baker, currently crushing rival managers returns with big tech stock bets, led the way as the mutual fund giant sold 1.85 million shares in Buffalo Wild Wings during the first quarter.

Activist hedge fund Marcato Capital Management, which owns 6 percent of Buffalo Wild Wings, has been courting big shareholders as it seeks to replace the company's chief executive officer, Sally Smith, and win board seats.

Wymer's $36 billion Fidelity Growth Company Fund owned no Buffalo Wild Wings shares at the end of March, according to the regulatory filing. At the end of February, the fund owned 368,831 shares; it had reported owning 600,000 shares at the end of 2016.

The fund's year-to-date total return of 15.75 percent is double the S&P 500's 7.74 percent gain, according to Morningstar Inc data, as of Thursday. Wymer has beat 83 percent of his peers during that period.

Baker's $14.8 billion Fidelity OTC Portfolio also held no Buffalo Wild Wings shares at the end of March, the filing shows. At the end of 2016, the fund owned 255,600 shares.

The OTC Portfolio's year-to-date total return of 19.78 percent is beating 99 percent of actively managed large-cap growth funds.

A Fidelity spokesman declined to comment.

Marcato last month ratcheted up the pressure on Buffalo Wild Wings by calling on Smith, who's held the top job since 1996, to retire and urging fellow shareholders to vote for its slate of four directors at the June 2 annual meeting. The hedge fund wants management to franchise more of its stores, increase sales and raise profit margins.

Buffalo Wild Wings' shares traded at $156.30 on Friday afternoon, up 1 percent for the year-to-date. Marcato has said that the share price could top $400 in the next four years if its plans for improvement are implemented.

Not all Fidelity managers have a negative view. Patrick Venanzi's $2.9 billion Small Cap Growth Fund built a new position of 205,200 shares during the first quarter. Buffalo Wild Wings accounted for 1.2 percent of the fund's assets.

(Reporting by Svea Herbst-Bayliss and Tim McLaughlin; Editing by Leslie Adler)

By Svea Herbst-Bayliss and Tim McLaughlin