Landmark Bank, Columbia’s oldest continually chartered national bank, was sold Wednesday to Pine Bluff, Arkansas-based Simmons First National Corp.

Based in Columbia, Landmark Bank parent company, The Landrum Company, has over $3 billion in assets and 39 locations in Missouri, Oklahoma and Texas. Simmons First National, parent of Simmons Bank, has $17.6 billion in assets and more than 200 locations in Arkansas, Colorado, Illinois, Kansas, Missouri, Oklahoma, Tennessee and Texas.

Simmons Bank spokeswoman Caroline Makris said the deal is valued at $434 million in Simmons Bank stock.

“This represents the largest individual bank Simmons purchased to date,” Makris said.

Landrum Company CEO Kevin Gibbens said the scale of Simmons Bank’s size will allow the combined company to offer better financial products for Landmark Bank customers.

“Simmons has grown to become an impressive regional bank known for successfully integrating its merger partners into its enterprise,” Gibbens said in a news release. “That gives me great confidence in our combined future.”

Exchange National Bank which became First National Bank of Columbia in 1964 and Landmark Bank in 2008, was opened as Columbia emerged from the Civil War in 1865. Boone County National Bank, which later became Central Bank of Boone County, opened in 1857 and received a national bank charter in 1863, but gave up its original charter in 1864. Central Bank resumed business in 1871.

Five years ago, Simmons Bank was the size of Landmark Bank, Makris said. Before the purchase, Simmons Bank had Missouri locations in St. Louis, Springfield and other parts of southwest Missouri. Like Landmark Bank, Makris said Simmons Bank has small town roots.

“None of the other markets currently overlap,” Makris said. “It was a really nice compliment to our geographic footprint.”

The deal marks the second Simmons Bank acquisition this year in Missouri. In the second quarter, Simmons Bank completed a $214 million cash and stock deal with St. Louis-based Reliance Bancshares, according to trade publication Talking Business & Politics.

During the fourth quarter of this year the two parent companies, the Landrum Company and Simmons First National, will merge. At that point, Landmark Bank will operate as a subsidiary of Simmons Bank until the two banks complete their merger in the first half of next year, Makris said.