SAP co-founder Hasso Plattner plans to sell shares in the German software company worth up to 240 million euros ($351.2 million) by the end of next year, the company said.

SAP said in a statement on Tuesday that Plattner had signed a deal with a bank to sell SAP shares with a fair value of 15 million euros each month until Dec. 31, 2010.

A spokesman declined to comment on the move.

Plattner founded the company in 1972 with four others and has reduced his stake several times, leaving him with a stake of 10.5 percent.

Based on SAP's market capitalisation of around 43.2 billion euros, selling 240 million euros worth of shares would lower his holding to around 5 percent.

(Reporting by Nicola Leske, Editing by Michael Shields)