On December 19, 1904, the state of Arkansas granted a charter which founded Pike County Bank in Murfreesboro. The capital stock totaled a whopping $25,000, which back in the day was quite a lot of money. That would come to around $692,172 in today’s dollars.

The bank built their first building on the lot west of the current Pike County Archives Building in Murfreesboro. By 1912, the bank built a brick building on its new site located at the northeast corner of the courthouse square. As Pike County Bank began to grow in the early 1950s, it expanded by adding a new branch office located in Mineral Springs (October 1951). In July 1979, the bank built another building in a new location where it exists today in Murfreesboro, east of the Murfreesboro Post Office at 319 East Main Street.

The Bainum Family, the late Irvin C. Bainum & Evea Bainum, purchased Pike County Bank on March 21, 1986. In August 1996, Pike County Bank changed its name to Diamond State Bank (Murfreesboro, AR) and at the same time Bank of Glenwood became Arkansas Diamond Bank (Glenwood, AR). In March 2007, two of Southwest Arkansas's strongest community banks merged to become what is known today as Diamond Bank.

Timeline of Diamond Bank branches added by the Bainum Family

• Nashville (Main Branch): July 1991
• Mount Ida: January 1994
• Dierks: October 1994
• Mena: April 1998
• DeQueen: July 1999
• Hot Springs (Lake Hamilton): November 1999
• Hope: May 2001
• Hot Springs (Lakeside): January 2008
• Nashville (Express Branch): July 2009
• Russellville: January 2016
• Ashdown: May 2017
• Texarkana: July 2017
• Hector: March 2019