COPENHAGEN, March 31 (Reuters) - Sweden's Fortnox said

on Monday its largest owner First Kraft and private equity group

EQT had made a joint cash offer for the accounting software

firm, valuing it at around 55 billion crowns ($5.51 billion).

Fortnox's board of directors unanimously recommended to

shareholders to accept the offer, it said in a statement.

The offer price of 90 crowns per share represents a premium

of 38% compared with its closing share price on March 28.

"EQT wants to support Fortnox's continued development, which

will require significant and long-term investments in product

development and potential M&A initiatives that involve

operational and financial risks," EQT said in a separate

statement.

($1 = 9.9856 Swedish crowns)

(Reporting by Stine Jacobsen; Editing by Anna Ringstrom and

Muralikumar Anantharaman)