By Gianluca Semeraro and Maria Pia Quaglia
MILAN, Nov 3 (Reuters) - U.S. financial services company Ameriprise Financial (NYSE:AMP) AMP.N has joined the race to buy asset manager Pioneer Investments, which has been put on the block by Italy's biggest bank UniCredit CRDI.MI , two sources close to the matter said on Thursday.
The Minneapolis-based company, which controls Threadneedle Asset Management, joins four other bidders that are expected to present binding offers for Pioneer by Nov. 10, the sources said.
Ameriprise and UniCredit declined to comment on the issue.
Europe's biggest asset manager Amundi AMUN.PA and an Italian consortium led by Poste Italiane PST.MI are seen as frontrunners in the race.
Australia's Macquarie MQG.AX and British group Aberdeen Asset Management ADN.L are also interested in the unit.
The sale of the asset gatherer is part of a broader effort by UniCredit to boost its capital. Led by its new CEO Jean-Pierre Mustier, the bank is due to unveil a new strategic plan on Dec. 13.
The offers will likely value Pioneer between 3.2 billion and 3.4 billion euros ($3.8 billion), another source said.
Poste Italiane has had contacts with both Aberdeen and Macquarie over joining forces to buy Pioneer but the talks have so far led nowhere, a fourth source said.
One of the sources said a further extension of the deadline for presenting binding offers could not be ruled out.
($1 = 0.9013 euros)