SAN FRANCISCO (AP) — If fewer people are interested in buying a new personal computer, then fewer investors want to own stakes in companies whose fortunes are tied to the sales of laptop and desktop machines.

That logic ruled Thursday as Wall Street reacted to fresh evidence that PCs are turning into a dying breed of technology as consumers and businesses embrace smartphones and tablet computers as their preferred computing devices.

The stocks of PC software maker Microsoft Corp. and PC maker Hewlett-Packard Co. absorbed significant hits on the news that PCs suffered an unprecedented sales decline during the first three months of the year. Other companies connected to the PC industry, such as Intel Corp., also were affected, although not to the same degree as the industry bellwethers.

Microsoft’s stock fell $1.35, or 4.4 percent, to close at $28.93, while HP’s shed $1.44, or 6.5 percent to finish at $20.88. Intel shares decreased 43 cents, or nearly 2 percent, to $21.83.

First-quarter shipments of PCs plummeted by 11 percent to 14 percent from a year earlier, according to separate estimates issued late Wednesday by Gartner Inc. and International Data Corp.

By either measure, it was biggest decrease recorded by either research firm since they began tracking PCs sales. For IDC, the data goes back to 1994 — just before Microsoft released a revamped PC operating system called Windows 95, which played a major role in triggering a sales boom that turned laptop and desktop machines into a household staple.

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