Black Knight appears to have struck first. CEO Anthony Jabbour said in a Nov. 6 analyst call that the company had filed a lawsuit the previous day “for breach of contract and misappropriation of trade secrets,” according to a transcript published by the Motley Fool.

Later on Nov. 6, PennyMac announced in a press release that it had filed its own lawsuit against alleging unfair competition.

The dispute centers around Black Knight’s market-leading LoanSphere MSP mortgage loan servicing system. Black Knight claims PennyMac, when it was a Black Knight client, used the system to “to unfairly accelerate the development testing and implementation” of PennyMac’s own system, while PennyMac claims Black Knight uses MSP to “both entrap its licensees and create barriers to entry that stifle competition.”