Chesapeake ( CHK) keeps drilling for profits in the same familiar way. The independent gas producer announced yet another big acquisition -- its fourth so far this year -- when reporting strong second-quarter results late Monday. Chesapeake plans to buy three private companies in a $590 million transaction financed with an equal mixture of equity and debt. The transaction furthers Chesapeake's strategy of relying on acquisitions for much of its profit growth. Fredric E. Russell, a money manager in Chesapeake's home base of Oklahoma, expressed some alarm on Tuesday. "When the universal thesis declares that energy prices have nowhere to go but up, and that we will face an energy crisis forever, I get concerned that companies may be buying at the top," said Russell, who has no position in Chesapeake's stock. "If you look back at every boom and bust since 1973, you'll see that acquisitions during periods of optimism have seemed to be a dangerous, risky strategy." Chesapeake itself has a history of placing huge bets during good times that have come back to haunt it later. The company's stock -- once a $30 highflier -- collapsed below $1 in the winter of 1998 as gas prices and its own drilling success faltered. But the company was quick to point out on Monday that its stock has rocketed some 1,525% since that difficult time. Still, investors were cautious on Tuesday. They pushed shares of Chesapeake down 3.4% to $14.65 during the morning session. Bob Rader, senior vice president of Capital West Securities in Oklahoma City, blamed the slide on the dilutive nature of the current transaction. Still, he described the deal as a good one. He pointed out that Chesapeake is acquiring the new reserves at about one-fourth of current gas prices. Thus, he says the company is now strongly positioned to profit from the transaction.