* Whole unit worth 2 bln euros - sources
* Offers are for 50 percent stake
* UniCredit selling assets to boost capital (Adds Advent Capital Management saying not involved; no comment from CVC and Advent International)
By Maria Pia Quaglia and Valentina Za
MILAN, July 30 (Reuters) - Italy's UniCredit SpA will receive three binding offers on Wednesday to buy up to 50 percent of its asset management unit Pioneer, two sources close to the matter told Reuters.
Like some other European banks, UniCredit, Italy's biggest lender by assets, has been selling assets to boost its capital base in preparation for a health check of euro zone banks. It most recently listed 34.5 percent of its online broker Fineco , pocketing 774 million euros ($1 billion).
"The (Pioneer) offers are for a 50 percent stake," one of the sources said. The unit as a whole is worth 2 billion euros, the sources said, speaking on condition of anonymity.
UniCredit declined to comment.
A report in Italian daily Il Messaggero cited Spanish bank Santander and U.S. groups CVC Credit Partners, part of CVC Capital Partners, and Advent Capital Management as three possible bidders.
A spokesman for Advent Capital Management denied the New York-based firm was involved.
Santander, CVC and U.S. private equity firm Advent International declined to comment.
Speculation that Pioneer was up for sale or could be floated has been doing the rounds for months, with UniCredit repeatedly denying this was the case and saying it considered the unit of strategic importance to its business.
UniCredit CEO Federico Ghizzoni said on July 9 the bank was ready to consider growth at Pioneer through partnerships, but ruled out a sale.
UniCredit had considered selling Pioneer in 2011 but dropped the idea after failing to conclude a tie-up with Eurizon, the fund manager arm of domestic rival Intesa Sanpaolo.
UniCredit, which reports first-half results on Aug. 5, posted a shock 14 billion euro loss in 2013 after taking huge provisions for souring loans - the number one problem for Italian lenders as the euro zone's third-biggest economy struggles to leave behind a painful recession.
In the first quarter of this year, its core capital ratio - a key measure of financial strength - stood at 9.5 percent, above the minimum 8 percent requirement set by the European central Bank but below that of Intesa Sanpaolo and other competitors.
One of the sources said the possible sale of part of Pioneer was likely to be discussed at the Aug. 5 board meeting but no decision was imminent.
"Time will be needed to discuss the offers and decide, we are talking after September," said the source, adding that the offers had not been solicited by the bank.
Il Messaggero said that, if the sale went through, UniCredit would keep management of the unit. ($1 = 0.7463 Euros) (Writing by Silvia Aloisi; editing by David Holmes and Keiron Henderson)