NEW YORK (CNN/Money) - National advertising spending is on the rebound, but is that enough to lift media companies' stocks when they report second-quarter earnings?

Four media giants are due to report results and offer guidance about the future in the coming days and some are expected to show reduced profits despite the revenue gains.

All the major broadcasters reported healthy gains in early ad sales for the fall television season -- known as the "upfront" market -- about 10 percent higher than the previous year.

"Programing costs remain high, the ratings challenges remain significant," said independent media analyst Jack Myers, author of "The Jack Myers Report." "To actually generate the revenue they've sold, the networks have to produce the ratings they've promised. But still the prognosis through 2004 is very strong, very bullish."

Still, the ad market is not quite as strong top to bottom as the upfront market suggests, said Paul Kim, independent media analyst with Kim & Co.

"National marketers are spending money but local businesses haven't been so far," he said.

AOL Time Warner (AOL: Research, Estimates), owner of CNN/Money, is the first major media conglomerate set to report earnings on Wednesday before the bell, followed by Viacom Inc. on Thursday. On July 31, Walt Disney Co. will release earnings and French media conglomerate Vivendi Universal will report its revenue for the most recent quarter.

At AOL Time Warner, it's the company's troubled online unit that will likely get more attention than its old-line media properties.

"We'll be looking to see what (America Online's) ad numbers look like, what they say about subscribers," said Kim. "Most people are looking for losses of 200,000 to 300,000 subscribers."

Analysts surveyed by earnings tracker First Call expect AOL to earn 10 cents a share, up slightly from 9 cents a share a year earlier. Revenue of $10.6 billion, up about 4 percent from year-earlier levels, is forecast. The company posted strong box office for its movie "The Matrix Reloaded," which did about $270 million in domestic ticket sales in the quarter.

"Film entertainment is fine for the next 12 to 24 months, you've got franchise films set to come out," said Kim. "It's something you don't have to think about."

What analysts will be thinking about more are asset sales and pending investigations into America Online's accounting practices by the Securities and Exchange Commission and Justice Department, probes that are delaying the initial public offering of a stake in the company's cable operations.

Viacom (VIA.B: Research, Estimates) is perhaps the least challenged of any of the major media companies right now. First Call's forecasts see EPS rising to 36 cents from 31 cents a year earlier, as revenue climbs about 7 percent to $6.2 billion.

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The parent of the CBS and UPN television networks also owns Paramount Studios, radio station unit Infinity Broadcasting and a number of key cable networks.

Unlike AOL Time Warner and Vivendi, which are trying to shed assets, Viacom has been on somewhat of a buying spree -- agreeing to buy the 50 percent stake it did not already own in Comedy Central from AOL Time Warner for $1.2 billion during the recently completed quarter, and paying $3 billion for BET cable network in 2001.

Besides looking for guidance on future ad dollars or cable revenue, investors will be listening for indications about its future acquisition plans, especially concerning some of the cable assets on the block at Vivendi Universal.

Walt Disney Co. (DIS: Research, Estimates) is expected to see EPS slip to 16 cents from 17 cents a year earlier, even as revenue climbs 5 percent to $6.1 billion.

The owner of ABC as well as ESPN and the Disney studio and theme parks will be hurt by weak performance at ABC, including miserable ratings for its first season of showing the NBA playoffs. The theme parks are also expected to show weak results.

The one bright spot for Disney is its stake in the surprise blockbuster hit "Finding Nemo," with which it shares the profits with Pixar Animation Studios. (PIXR: Research, Estimates) The animated film had domestic box office of about $250 million in the quarter and now is expected to top the $300 million mark.

Disney's shares have performed better than its bottom line, gaining more than 25 percent for the year. Kim, who has a sell recommendation on Disney as well as on AOL Time Warner and Viacom, thinks investors are getting ahead of themselves in the sector.

"Enough people are saying, 'When there's an economic turnaround, the media company with most leverage to benefit from that is Disney.' People are putting their money on turnaround," he said. Kim does not own stock in any of the media companies he follows.