Patsystems, the London-based derivatives software firm, has warned that bankrupt MF Global owes it nearly a million pounds.

As the vendor faced heightening financial troubles, it received a takeover approach from its largest shareholder, ION Trading, valuing it at £29 million.

Patsystems provides electronic trading software to broker-dealer MF Global, its largest client, and initially calculated that the collapsed company owed it approximately £300,000.

But since conducting further analysis as the MF Global situation unravelled, Patsystems calculated it was owed at least £900,000.

Administrators at MF Global in the UK, meanwhile, have abandoned its automated accounting record systems - because unwinding the finances has become so complicated that records will no longer fit the software's formatting. Around 300 processing and client reconciliation staff remain.

Patsystems, hit hard by the collapse of MF Global, responded positively to the ION Trading approach, highlighting in a statement the "strong commercial fit with ION, their greater financial stability, as well as the potential benefits to staff, customers and product development".

John O'Brien, research director at analyst house TechMarketView, said he was not surprised at Patsystems' reaction, given its financial challenges.

"Looking at Patsystems' current predicament it's not hard to see why management are so keen," he said, noting the sustained slump in Patsystems' shares since it first announced how much it was owed by MF Global.

"For Patsystems, ION's approach is clearly a very welcome piece of good news," he said.

Patsystems is in discussions with MF Global's administrators regarding the money it calculates it is owed. It has not speculated how much of the money it expects to recover.