Core processing specialist Corelation Inc. has signed its fifth and by far largest credit union client.

The $535 million Orion FCU in Memphis, Tenn., is larger than the San Diego startup’s first four clients combined.

The other four are all under $100 million in assets and in California and Oregon.

The Tennessee credit union’s conversion to Corelation’s KeyStone platform is expected to take place in August, the company and credit union said.

Unlike the first four customers, which were all Symitar customers, Orion is currently on a Fiserv Spectrum platform, according to the Technology Survey from Callahan & Associates.

The KeyStone platform was developed by John Landis, one of the creators of the original Symitar platform and a founder of that company and of Corelation.

“The current system we are on is antiquated and time-consuming in its processes, which is a major hindrance for competition,” said Daniel Weickenand, CEO of Orion FCU, which changed its name in June from Memphis Area Teachers Credit Union. “Conversely, we see Corelation benefiting both our credit union and our members with its efficiency, efficiency and more efficiency.”