A bidding war could be brewing for HCA ( HCA), according to published reports.The Wall Street Journal reported that private equity firm Blackstone is mulling an offer for the hospital chain just days after HCA agreed to a $21 billion buyout by a group led by Bain Capital, Kohlberg Kravis Roberts and Merrill Lynch. The Journal, citing a person familiar with the matter, said Blackstone's deliberations are in the early stages. The paper pointed out that a rival bidder might find the going tough due to the terms of the Bain-HCA agreement, which calls for a rich breakup fee and gives the buyers the right to match any offer. But private equity firms such as Blackstone are known to have deep pockets and HCA is seen as the plum property in the staggering hospital business. Bain and KKR said Monday they intend to grow the business rather than depending on steep cost cuts, as leveraged buyers often have in the past.