A big investor in Flagstar Bancorp is reducing its stake in the Troy, Mich., company.

The $26.8 billion-asset Flagstar disclosed in a regulatory filing Monday that MatlinPatterson plans to sell 6 million shares of stock in a secondary offering. The investor could sell another 900,000 shares if there is enough demand.

The pricing has not been determined.

MatlinPatterson’s stake in Flagstar will decrease from 36.2% to 25.6% stake after the sale is completed.

The investor, which once owned more than 60% of Flagstar’s stock, has been gradually reducing its holdings in the company.

Flagstar will not receive any proceeds from the sale.