Investors didn’t take too kindly to Macrovision’s $2.8 billion deal to acquire Gemstar-TV Guide International, sending shares of both companies swooning yesterday on the news.

The stock of piracy-protection maker Macrovision took a pounding, dropping 21 percent, or $5.55, to close trading at $20.44.

While it is common for the stock of an acquiring company to fall on deal news, the fact that Gemstar’s shares also shed 16 percent, or 99 cents, to close trading at $4.99 suggests that the deal might have a hard time obtaining shareholder approval.

A majority of Macrovision shareholders and two-thirds of Gemstar shareholders need to vote for deal for it to close. News Corp., which owns The Post, has already agreed to vote its 41 percent stake in Gemstar in favor. The boards of both companies also unanimously approved the deal.

Several sources confirmed that at various points during the five-month long sale process Liberty Media, EchoStar, TiVo, Comcast, Microsoft, Google, Motorola, Qwest, Verizon, and Cisco, as well as private equity firms, all looked at Gemstar.

To be sure, perhaps sensing that market reaction might be negative, on announcing the deal both companies reminded investors that Gemstar’s “extensive review” of strategic alternatives included a “broad solicitation of interest.”

Sources said a deal for Gemstar would have been completed sooner had it not been for a surge in the company’s stock price over the last two months.

The shares, which had traded in the $4-$5 per share range for most of the year, hovered above $6 for much of the fall, hitting a high of $7.15 on Oct. 26 and scaring off potential buyers.

Much of Gemstar’s value is tied to the annuity revenue generated by the portfolio of patents amassed under former CEO Henry Yuen related to its interactive television programming guides.

Yuen was removed as CEO and ordered to pay $22 million to settle civil charges related to accusations of accounting irregularities at Gemstar while he was in charge.

Sources said many of the companies that looked at Gemstar felt that TV Guide magazine’s value was low and that growth prospects for its similarly-named cable network had hit a wall. They therefore based their bids on the value of Gemstar’s intellectual property alone.

Terms of the deal call for Gemstar shareholders to receive either $6.35 in cash or 0.2548 of a share of common stock in a new company for each Gemstar share held.

That’s a 29 percent premium to Gemstar’s stock price prior to the beginning of its strategic review in July.

The cash portion of the deal won’t exceed $1.55 billion and Macrovision said it would raise $800 million of new debt to fund the purchase.

Macrovision shareholders will get one share in the new company for each share owned.

plauria@nypost.com