New York ? In the 11 years that the WB and UPN have both struggled for life, it wasn’t difficult to see that between them they probably had enough assets to make one strong television network.

The business leaders in charge of them have finally concluded the same thing.

They announced Tuesday they’ll shutter the WB and UPN and this fall start a new network, the CW, that will combine the assets of both. It’s a 50-50 venture between the CBS Corp., which owns UPN, and Warner Bros. Entertainment.

“We are starting a new network with programming that we already know works,” said Dawn Ostroff, UPN president, who will be programming chief for the CW.

With varying degrees of success, both networks have courted the same young audience. The new CW will similarly target an audience aged 18 to 34, said Leslie Moonves, CBS president.

Shows like “America’s Next Top Model,” “Smallville,” “Everybody Hates Chris” and “Gilmore Girls” are likely to have the same address.

The idea grew out of a dinner last fall between Moonves and Barry Meyer, Warner Bros. Entertainment chairman. The two are old friends and Moonves has described Meyer as a mentor: before running CBS, Moonves ran the Warner Bros. television studio, developing hits like “ER” and “Friends.”

UPN has never turned a profit in its 11-year history. The WB has had a couple of profitable years, but executives involved concluded the long-term prospects apart didn’t look nearly as strong as they would have together. They began secretly working out the business plan – so secret that UPN and WB executives were outlining their fall programming plans to television writers last week in Pasadena, Calif.

The WB had a few strong years when series like “Dawson’s Creek” made it a hip destination for young viewers, particularly teenage girls.

They reflected the strong programming hand of chief executive Jamie Kellner. But since Kellner retired a few years ago, the WB has tried to broaden its audience and, in the eyes of many critics, lost much of its identity in the process.

This season, there were clear signs of financial struggle. The WB announced it was canceling “7th Heaven,” the family drama that was the network’s most successful show ever, because it would cost too much to continue production.

After many years of floundering, UPN has grown stronger under Ostroff in recent years with critical hits like “Veronica Mars” and “Everybody Hates Chris.”

UPN devotes one prime-time night to wrestling – that will continue at the CW – and on Monday its comedies target primarily a black audience. Ostroff has pulled in vanity projects from big stars: “Everybody Hates Chris” is about comic Chris Rock’s youth, “All of Us” is loosely based on Will Smith’s life and “South Beach” is executive produced by Jennifer Lopez.

The WB’s strongest assets now are “Gilmore Girls,” although it is nearing the end of its run; the freshman drama “Supernatural;” and the reality show “Beauty and the Geek.”

Both the WB and UPN began operating within two weeks of each other in 1995, and will go out together.

The new network’s name is a combination of their corporate ownership: “C” for CBS and “W” for Warner Bros.

“We couldn’t call it the ‘WC’ for obvious reasons,” Moonves said. WC is an abbreviation of the British term “water closet,” or toilet.