MILAN, Nov 1 (Reuters) - Shares in Monte dei Paschi di Siena (MPS) rose sharply on Tuesday after the bank said it had found investors to cover 93% of its capital increase despite low shareholder take-up.

The capital raise, which had appeared in doubt because of difficult market conditions, ends on Thursday when a deadline expires to exercise leftover rights to buy into the bank's cash call.

Those rights are being auctioned on the Milan bourse on Tuesday and Wednesday.

By 1122 GMT on Tuesday shares in MPS had gained 4.7% to 2 euros, returning to the price at which new shares are being sold.

The subscription period for existing shareholders concluded on Monday, when MPS said it had raised 1.847 million euros including the 1.6 billion euros paid by Italian taxpayers based on the state's 64% stake in the bailed-out bank.

That meant that other shareholders, comprising many retail investors, have snubbed the bank's seventh cash call in 14 years.

Though stakeholders other than the state contributed less than 250 million euros, the take-up level rises to 93% when taking into account sub-underwriting accords worth 475 million euros, MPS said.

A source with knowledge of the matter confirmed an Italian press report indicating that payments group NEXI is among the commercial partners helping out, contributing 20 million euros.

With underwriters unwilling to bear risks for more than half the 900 million euro private portion of the capital increase, MPS had been forced to secure sub-underwriting commitments from investors including its commercial partners and holders of its junior debt, including U.S. bond giant Pimco.

MPS junior bonds have recovered since trading at half their nominal value because of the risk of conversion into equity. On Tuesday they traded at between 70% and 80% of face value.

Sub-underwriters will receive 25 million to 30 million euros in fees out of a total of 125 million euros MPS will pay to underwriters, said two people close to the transaction.

The fees are unusually high to compensate investors for the risk of losses, given that the new shares value MPS above healthier rivals.

To further reduce the amount of unsold shares, the Treasury has enlisted the help of more banking foundations to take up unexercised rights. (Reporting by Valentina Za Editing by David Goodman)