Richmond, Va.-based Union Bankshares Corp. has agreed to acquire Reston, Va.-based Access National Corp. in an all-stock transaction.

Under the terms of the deal, each outstanding share of Access common stock will be converted into the right to receive 0.75 shares of Union common stock, valuing the transaction at approximately $610 million, or $29.19 per share based on Union's Oct. 4 closing stock price of $38.92.