Updated from July 23HCA ( HCA) rose 4% early Monday after the hospital chain agreed to a $21.3 billion take-private deal. HCA said a private equity group led by Bain Capital, Kohlberg Kravis Roberts and Merrill Lynch will buy HCA for $51 a share, an 18% premium to HCA's price before news of the talks emerged last week. The deal is valued at $33 billion including HCA's debt, making it the biggest-ever leveraged buyout on that basis. "After careful analysis, the special committee and the board have endorsed this transaction as being in the best interests of our shareholders," HCA chief Jack Bovender said. "We are very pleased to have an experienced group of investors who are committed to maintaining our company's culture of a patients-first approach to high quality, compassionate care. They are also committed to the welfare of our colleagues across the company who carry out that mission every day. These are the principles on which HCA was founded." Under the merger agreement, HCA may solicit superior proposals from third parties during the next 50 days. In accordance with the agreement, the board of directors of HCA, through its special committee and with the assistance of its independent advisors, intends to actively solicit superior proposals during this period. The buying group also includes HCA management and the founding Frist family. Senate Majority Leader Bill Frist is a member of the family and is being investigated for the timing of his sales of HCA stock in mid-2005. HCA shares rose $2.09 early Monday to $49.96.