With much speculation that a fifth TV network will spring from the merger of QVC Network and the Home Shopping Network, some savvy investors are cleaning up whether the new web appears or not.Very quietly, shares in former HSN subsidiary Silver King Communications have skyrocketed 15-fold in price since December. However, Silver King’s attraction is somewhat speculative. Its biggest asset is 12 UHF stations serving eight of the largest TV markets in the U.S., including New York, L.A. and Chicago. All told, those stations reach 27.5 million households. Must-carry advantage In addition, the stations, which broadcast HSN’s signal to areas not carrying the channel on cable, could soon be freed up for other programs. A recent federal ruling under the new cable act put HSN under the must-carry provision, forcing cable franchises to put the shopping channel on their dial. Repeat performance Under the guidance of QVC chairman Barry Diller, who masterminded the creation of the fourth network, Fox Broadcasting Co., a repeat performance isn’t far-fetched. But analysts wonder if investors aren’t jumping the gun. There is a serious regulatory hurdle to clear. Silver King was spun out of HSN to its shareholders on Dec. 28, just two weeks after Liberty Media Corp. acquired control of the home shopping channel. Liberty, which owns substantial stakes in a host of cable programmers and MSOs, couldn’t hold onto Silver King because federal rules prevent cross-ownership of cable and broadcast properties in the same market. Instead, it paid Silver King’s largest shareholder, Roy Speer, $ 2 million for an option to buy effective control. “The whole speculation was that Diller would use Silver King to launch a fifth network,” said John Field, a cable analyst at Hanifen Imhoff Inc. in Denver. “But this doesn’t acknowledge the fact there’s cross-ownership prohibition. That’s why there’s the Liberty option, because Liberty couldn’t own it. The (stock) run-up is misplaced.” Watchdog warning If there were a change in federal regulations, worries Andrew Jay Schwartzman , executive director of the Washington-based Media Access Project, a regulatory watchdog, Liberty “would have stations with must-carry rights that put them in 60% to 70% of TV households in some of the largest markets — that’s an awesome head start.” Liberty has two years to exercise its Silver King option, but it could take that long for the FCC to change its rules banning cross-ownership. Silver King itself has speculated that the option could be assigned to a third party. Someone who fits the bill could be Barry Diller.