NEW YORK — The McClatchy Co. is making its biggest bet yet on the future of the newspaper industry by agreeing to pay $4.5 billion in cash and stock to acquire Knight Ridder Inc., a major newspaper publisher more than twice its size.

The addition of The Miami Herald, Fort Worth Star-Telegram and 18 other papers in fast-growing cities may be less risky than it seems. McClatchy CEO Gary Pruitt said in an interview yesterday that all the papers are dominant in their markets and ripe for rapid expansions of their Internet and direct-mail businesses, without requiring deep cuts in newsgathering budgets.

But Pruitt also is counting on paying down acquisition debt quickly by selling The Philadelphia Inquirer, the San Jose Mercury-News and 10 other Knight Ridder newspapers. Those properties don't meet Sacramento-based McClatchy's growth-market criteria — or in the case of the St. Paul Pioneer Press, compete directly with McClatchy's Star Tribune in neighboring Minneapolis.

The takeover would be the second-largest in U.S. newspaper history, topped only by the Tribune Co.'s $6.5 billion acquisition in 2000 of Times Mirror Co. After the divestitures, McClatchy's 32 newspapers would be second nationwide in daily circulation behind Gannett Co. Inc. (publisher of The Honolulu Advertiser), and rank fourth in revenue behind Gannett, Tribune and The New York Times Co.

Pruitt, a youthful looking 48-year-old, said he doesn't anticipate any problems selling the newspapers, which he said could possibly coincide with the anticipated closing of the Knight Ridder purchase in the summer.

Analysts generally agreed they likely will be sold quickly. Gannett and William Dean Singleton's MediaNews Group Inc., which owns The Denver Post and other newspapers, earlier considered making bids for Knight Ridder and are viewed as potential bidders. Gannett declined to comment, and MediaNews didn't return a call seeking comment.

In addition, "There are some deep-pocketed guys who want to own newspapers," said industry analyst Edward Atorino, who noted that New York's two tabloids are controlled by Rupert Murdoch and real-estate developer Mort Zuckerman.

McClatchy, which normally keeps debt levels low, is taking on $3.75 billion in bank debt as well as $2 billion in debt from Knight Ridder. But Pruitt said the company expects to retain its investment-grade rating on its debt by quickly moving to reduce its debt ratio below four times its cash flow.

The deal would produce about $60 million in annual savings, largely from consolidating corporate functions and some centrally operated Internet operations, he said. Pruitt added that he does not anticipate any layoffs at the newspapers as a result of the transaction, though he said the Washington news bureaus of the two companies would be combined, again without layoffs.

"These are high-quality papers. They're doing well, and we expect to sustain and further their journalism," Pruitt said.

Newspaper stocks have been out of favor on Wall Street recently over concerns about declining circulation trends, the competitive threat from the Internet and other concerns, including the rising cost of newsprint.

Those concerns were evident in stock market trading yesterday. McClatchy shares fell $1.51, or 2.9 percent, to $51.55 in heavy trading on the New York Stock Exchange after earlier declining to as low as $49.21 a share. Knight Ridder's shares fell $1.08, or 1.7 percent, to $63.92.

Based on yesterday's closing price, the deal values San Jose, Calif.-based Knight Ridder at $66.38 per share, including $40 per share in cash and 0.5118 of a share of McClatchy's Class A stock. Yesterday's decline in McClatchy shares sliced about $60 million from the total value of the deal.