NEW YORK (CNN/Money) - Viacom Inc. is buying the 50 percent of cable network Comedy Central that it doesn't already own from joint venture partner AOL Time Warner Inc. for $1.23 billion, the company announced Tuesday.

Viacom (VIA.B: Research, Estimates), a media conglomerate whose businesses include broadcast television network CBS, movie studio Paramount Pictures and radio broadcaster Infinity Broadcasting, said Comedy Central will join its MTV Networks unit's lineup of basic cable channels.

Viacom said the deal would add to earnings per share, although it did not quantify the impact. Separately Viacom reported improved first quarter earnings Tuesday that edged past Wall Street expectations, as the company said it was on track for further earnings and revenue growth this year.

AOL Time Warner (AOL: Research, Estimates), the parent company of CNN/Money, has been looking at the sale of non-core assets as a way of cutting about $26 billion in debt. It has confirmed that it is also looking at the sale of its book publishing unit, its Warner Music division as well as three professional sports teams base in Atlanta.

Shares of AOL gained 31 cents to $13.21 in pre-market trading on Instinet Tuesday following the announcement of the sale, after gaining 30 cents in regular-hours trading Monday. Shares of Viacom have yet to trade on Instinet in the pre-market. Shares of its more widely-traded class B stock closed up 13 cents to $40.84 on Monday.

The company is also facing Securities and Exchange Commission probes into its accounting practices, including some of its Internet advertising deals. Newspapers reported Tuesday those probes are expanding.

Comedy Central, which reaches 82 million U.S. homes, was launched on April Fool's Day 1991 after Home Box Office, owned by AOL Time Warner, merged its Comedy Channel with MTV Networks' HA! comedy network, owned by Viacom.

The network, one of the few examples of a successful media joint venture, has gained a reputation for continuing to push the limits of what can be broadcast on TV with sharp political satire and increasingly popular gross-out humor.

It has humorously covered political events and introduced original shows, such as "Mystery Science Theater 3000" and "Politically Incorrect," each of which garnered Emmy Award nominations and eventually landed on other networks.

Cable networks -- so-called content -- have fetched lucrative prices over the past few years as entertainment companies and cable providers chase programming to provide to viewers. AOL and Viacom do not provide separate financial results for Comedy Central.

However, Walt Disney Co. (DIS: Research, Estimates) paid a rich premium for Fox Family, as did General Electric Co. (GE: Research, Estimates)-owned NBC for Spanish-language network Telemundo, and arts channel Bravo in separate deals.

AOL Time Warner and Viacom had been talking for at least four months about a possible deal, but disagreed on a valuation for Comedy Central, sources said.  

Reuters contributed to this story