Investors Savings Bank, a large Richmond-based savings and loan, will gain a foothold in the lucrative Northern Virginia market by acquiring United Savings Bank of Vienna, the two companies announced yesterday.

In a complicated three-way deal, Investors Savings said it would pay $40.7 million in cash and stock to shareholders in United Savings. As part of the deal, Investors will also pay cash and stock worth $10 million to shareholders in Severn Savings Bank, a small Annapolis-based company that previously had agreed to a merger with United Savings but had not yet closed the deal.

The merger, which is subject to approval by state and federal regulatory authorities, will result in a new institution with 59 branches in Virginia and Maryland and assets totaling nearly $2.4 billion, according to a statement yesterday.

The deal will be worth $28 per share of United Savings stock, well above the $9.50-to-$11.50 that the stock has recently been trading for, according to Christopher W. Burch, United Savings' executive vice president. He said the two largest United Savings shareholders are the insurance firm USLICO Corp., which owns a 13.7 percent block, and a company controlled by Bethesda developer Albert Abramson, which owns 9.9 percent.

Referring to two of Virginia's major commercial banks, Burch said the merger "emphasizes the fact that the Crestars and the Signets can be competed against, and we intend to."

Burch said the combination will give the new institution "a tremendous competitive advantage" in the hotly contested Northern Virginia market, where Perpetual Savings bank and Dominion Federal Savings and Loan Association, among others, already have strong positions. "It will enable us to build our retail branch network in shorter order than by remaining independent," Burch said.

For Investors, which bought Richmond's Citizens Savings and Loan in 1986, the acquisition of United Savings marks the second major purchase in two years and provides a presence across the state, except in Roanoke and the southwest part of the state, according to Cary Morris, senior vice president for corporate administration. "Coverage in Northern Virginia was something that was going to happen," he said.

United Savings' 13 branches will be converted to the Investors' name, according to Burch. But he added that it is expected that most, if not all, of United Savings' 300 employes will be able to keep their jobs. The chairman of Investors, Robert G. Butcher Jr., will become chairman of a new holding company for the three banks' operations after the merger, while United Savings president Howard D. Orebaugh, will become president of the holding company and chief executive of Investors Savings Bank.