U.S. Markets close in 5 hrs 50 mins

Lexmark buys founders' stakes in Readsoft, ups its own bid

* Lexmark owns 35.4 pct of shares after buying founders' stakes

* Raises bid for Readsoft shares to 57 SEK/share

STOCKHOLM, Aug 20 (Reuters) - Lexmark on Wednesday raised its offer for Readsoft for the fourth time after buying stakes from the Swedish software firm's founders, the latest turn in a bidding war against Ohio-based software developer Hyland.

The printer maker said in a statement it had bought all shares held by Readsoft founders Lars Appelstal and Jan Andersson for 57 crowns per share, and raised its offer to that amount, in accordance with takeover laws.

The takeover battle for the Swedish company, which makes business software for processing invoices and sales orders, has proved lucrative for its shareholders. The new bid means a premium of 210 percent compared to the closing price of Readsoft shares the day before Lexmark launched its first offer of 40.05 crowns per share in May.

Lexmark's on Aug. 5 offered 55.50 crowns per Readsoft share, topping Hyland's latest offer of 55 crowns the day before.

After buying the founders' shares, Lexmark owns 35.4 percent of Readsoft shares, and 52.2 percent of votes, the company said. Hyland said earlier this month it controlled 10.9 percent of Readsoft shares. A spokesperson for Hyland declined to comment on Lexmark's move.

The new bid values Readsoft at 1.75 billion Swedish crowns($254 million) (1 US dollar = 6.8986 Swedish crown) (Reporting by Sven Nordenstam; Editing by Alistair Scrutton)