Boston-based mutual fund giant MFS Investment Management has decided to cut 90 jobs, or 5 percent of its current workforce, due to a decline in assets under management.

The company said the move was part of an effort to keep costs “in line with revenues” and all the layoffs will occur among employees who work at offices in Boston and Quincy. MFS employs approximately 1,800 people.

The cuts make MFS the third major Boston investment firm to eliminate jobs recently along with Fideltiy Investments and Putnam Investments. MFS's last round of job cuts came during the last bear market of 2002, when it laid off about 135 people out of a total work force of 2,700.

However, the company declined to comment on whether the company plans for more cost cutting in the near term.

MFS, which is owned by Canada-based Sun Life Financial, had $162 billion in assets under management at the end of September, down 20 percent from the $204 billion under management a year earlier.