The Ballston branch of Alliance Bank. (Jeffrey MacMillan/FOR THE WASHINGTON POST)

After more than a year and half on the market, Chantilly’s Alliance Bank has been purchased by Reston-based WashingtonFirst Bank for $24.4 million in a deal that was finalized Dec. 21.

The purchase nearly doubles WashingtonFirst’s assets from $596 million to $1.1 billion, and adds five Northern Virginia locations to the bank’s current line-up of 10 branches.

Alliance Bank’s “footprint fit almost perfectly with our plans to grow in Northern Virginia,” said Richard Horn, general counsel for WashingtonFirst Bank.

The two banks had been in talks for about a year, Horn said. Three Alliance Bank directors, including Chairman Donald Fischer, will join the board of WashingtonFirst.

Alliance Bank shareholders can choose to receive either 0.44 share of WashingtonFirst common stock or $5.30 in cash for each share they own.

In the run up to the purchase, WashingtonFirst raised about $27.1 million from investors to pay for the acquisition. Shares of WashingtonFirst Bank began trading on the Nasdaq stock market last week, but Horn said the bank does not have any immediate plans to expand further.

“We’re going to focus on assimilating this transaction,” he said. “Our organization is founded upon a measured growth strategy.”

In July 2011, Bethesda-based Eagle Bank had announced plans to buy Alliance Bank for $31.2 million, or $6.11 a share. Eagle Bank called off the deal in December, citing irreconcilable differences.

The acquisition follows a spate of community bank mergers in the region.

In 2012 alone, First Community Bank in Bluefield purchased Richmond’s Peoples Bank of Virginia for $40.6 million; First Virginia Community Bank in Fairfax bought Arlington’s 1st Commonwealth Bank of Virginia for $3.7 million; and Bowie-based Old Line Bancshares acquired Washington Savings Bank, also based in Bowie, for $49 million.