Excite@Home Corp. agreed to buy IMall Inc. for about $425 million in stock to expand its online shopping area and boost revenue. Excite@Home, whose biggest shareholder is AT&T; Corp., will exchange 0.46 share for each share of Santa Monica-based IMall. That values IMall at about $22.97 a share based on Excite@Home's stock price Tuesday. Redwood City, Calif.-based Excite@Home, a provider of Internet services through cable television wires, will add IMall, with merchants such as Macy's and Disney Store Online, as it moves beyond providing high-speed Internet access and adds content to its Web sites. Excite@Home also said it will work with a First Data Corp. unit to help merchants set up online stores in an effort to better compete with rivals such as Yahoo Inc. Shares of Excite@Home fell $1.56 to close at $49.94, while IMall shares fell 31 cents to close at $22. Both trade on Nasdaq.