First Security Corp. signed an agreement this week to acquire the deposits of MountainWest Financial's three Ogden branches.

First Security Chairman Spencer F. Eccles said MountainWest's Ogden deposits will be combined with First Security Bank of Utah, which currently operates 93 offices in 52 communities statewide. MountainWest Financial currently operates three offices in the Ogden area with deposits of $33 million.MountainWest's Salt Lake branches are not affected.

David C. Richard, MountainWest Financial's president and chief operating officer, said that because approval of the sale is pending by regulatory agencies, no precise date for the transfer has been set. "It is anticipated that completion of the transaction could take place by year-end," he said.

"In the meantime," Richard said, "our customers will continue to find business conducted as usual with no disruption of quality service at MountainWest offices. Normal business hours will be observed and the offices will continue to operate as they have in the past."

Eccles termed the deal "another important acquisition for First Security. We have announced four acquisitions in Utah in less than a year to extend our coverage of certain strategic markets in the state."

First Security operates 183 full-service banking offices in Utah, Idaho, Oregon and Wyoming. Other subsidiaries include a leasing company, two insurance companies, an investment management firm and a discount brokerage.