U.S. software firms SunGard Data Systems and Fiserv Inc top the list of suitors expected to submit bids for UK software company Misys by a deadline set for later this week, sources close to the matter said on Monday.

The two firms have been conducting due diligence checks on Misys since the end of July, when the UK firm said it had received a number of indicative offers for all or part of the company from a number of third parties including its management.

Earlier, shares in Misys rallied as much as 3 percent to an intra-day high of 258 pence on market talk that a 275 pence bid was likely for the company, traders said.

The shares closed up 1.5 percent at 254p a share, valuing Misys at 1.40 billion pounds ($2.67 billion).

We don't comment on market speculation, a Misys spokeswoman said.

The bid deadline had been set for this Friday and no bids had yet been received, the sources said.

Another potential bidder is UK private equity firm Permira, which had earlier submitted a bid with U.S. investment firm General Atlantic Partners, one of the sources said.

Permira is likely to back Misys's management, led by Chief Executive Kevin Lomax, in a bid, although it was not immediately clear if the group intends to submit an offer by Friday's deadline since Permira's previous bid was lower than both Fiserv's and Sungard's, another of the sources said.

Permira declined to comment.

Meanwhile, Fiserv and Sungard's bids could be complicated by the fact that both firms would want Misys's financial software business but are less likely to want to keep its healthcare division, which means finding a partner to sell the unit to.

Getting a joined-up bid for a public company with cash certainty is very hard, the source said.

No one at Fiserv or Sunguard was immediately available to comment.

In July Misys announced a sharp fall in pretax profits to 39 million pounds ($72 million) from 61 million a year ago on a 12 percent rise in total revenue to 953 million pounds.

Adjusted earnings per share (EPS) dropped to 14.3 pence from 14.8 pence a year last time, while operating profit was down 22 percent at 56 million pounds.

In March, it ended talks to sell its financial support services arm Sesame and said it would look to offload non-core activities to focus on its key areas of health and wealth.

(Additional reporting by Anshuman Daga and Jonathan Cable)