Hospital operator Community Health Systems Inc. on Monday revised its $3 billion offer for rival Tenet Healthcare Corp. to an all-cash bid.

Community Health is now offering $6 per share in cash. In December, it had gone public with a bid of $5 per share in cash and $1 per share in stock. At the time, the offer was a premium of about 40 percent to the Dallas company's shares.

But Tenet's board rejected that offer, and adopted a "poison pill" measure to fend off the bid.

Tenet's shares have recently been trading above $6.

But the company said Monday it will review the revised offer and make a recommendation. It said shareholders should take no action for now.

Tenet shares fell 26 cents, or 3.9 percent, to $6.40 in afternoon trading while Community Health shares dropped $1.74, or 5.5 percent, to $30.16 after falling as much as 14.3 percent earlier in the session.

Community Health Systems runs 130 hospitals in 29 states, and focuses on fast-growing and non-urban markets. Tenet runs 50 hospitals spread across 11 states, and most of its facilities are in urban and suburban communities.