UPDATE 1-Mass. pension fund beats August, YTD benchmark

(Adds details on executive director's added duties)

BOSTON, Oct 2 (Reuters) - The $50 billion Massachusetts state pension fund returned 1.27 percent in August, narrowly beating its benchmark on strong performance from global stock funds, according to a monthly report released on Tuesday.

For the first eight months of the year the fund was up 8.2 percent, beating its benchmark by 36 basis points, the report said.

"For the calendar year, five of seven asset classes are outperforming their respective benchmarks, which indicates that our investment managers are performing well," said Michael Trotsky, executive director of the Massachusetts Pension Reserves Investment Management Board.

Trotsky, meanwhile, has agreed to take the added duty of being the pension fund's chief investment officer. His base annual pay will be increased to $295,000 from $245,000.

After a discussion led by Massachusetts Treasurer Steve Grossman, the pension fund's board on Tuesday approved the combined role for Trotsky.

Grossman, who made the proposal, said the move will save the pension fund up to $195,000 in base salary. Some of the money, though, could be used to attract other key investment professionals for the pension fund, he said.

Trotsky assumes duties that were left open when long-time chief investment officer Stanley Mavromates took a job in the private sector earlier this year.

On Mavromates' watch, the pension fund amassed a track record of some of the best returns for public funds in his dozen years at the pension board.

(Reporting by Tim McLaughlin; Writing by Ben Berkowitz; Editing by James Dalgleish)