IN a move aimed at closing the ratings and buzz gap with the Disney Channel, Viacom’s Nickelodeon is about to announce a management shake-up that would strip Margie Cohen of her duties as head of the network’s animation studio in Los Angeles, The Post has learned.

According to a source inside the network, Nickelodeon plans to name Brown Johnson, who is currently in charge of Nick Jr., to head the animation studio. Cohen would take over Nick@Nite as part of the shuffle, although that part of the shake-up hasn’t been finalized yet, this source said.

The changes at Nickelodeon come as rival Disney, which is riding a wave of hits that includes “Hannah Montana,” “Cory in the House,” and the “High School Musical” franchise, is set to debut “Phineas and Ferb” next month.

Though Nickelodeon averaged more viewers during the entire programming day last year than the Disney Channel – 2.1 million versus 1.6 million – Disney dominated in primetime, averaging 2.7 million viewers to Nickelodeon’s 2.4 million, according to Nielsen Media Research. (Officially, Nick’s programming day ends at 8 p.m.)

Nickelodeon can ill afford to lose more ground to Disney and the source said network brass is concerned that its rival may have another hit on its hands because, “Disney really invested in it and feels bullish about it.”

Part of the reason for the management change is because Nickelodeon’s in-house production team is struggling to develop the next generation of hits. The Viacom network’s most popular show in the ratings is still “SpongeBob SquarePants,” and its most recent breakthrough program, “The Naked Brothers Band,” was developed by an outside production house.

“[We] are scrambling to figure out a formula because we are really hurting in the product development pipeline,” said the source.

Nickelodeon placed 19 programs in cable’s Top 40 last week, but they covered only three different series and 14 of them were “SpongeBob” episodes. By contrast, though Disney only had 10 programs in the Top 40, they spanned six different shows.

Though Johnson has helped shepherd such hits as “Blue’s Clues” and “Dora the Explorer” onto the air, elevating her to head the very visible animation studio is by no means a slam-dunk.

“It’s a risk because there’s a question of whether she can quickly adapt to the Nickelodeon sensibility coming from Nick Jr.,” said the source. A Nickelodeon spokesman declined comment for this story.

Peter Lauria

Bad investment

Individuals and institutions which handed over their money last year to famed and highly respected investor Henry L. Druker are probably scratching their heads this weekend after learning the Druker/McCombs Fund LP turned in a disappointing 4.0 percent gross return in 2007.

That’s barely better than the 3.53 percent return on the S&P 500 and worse than the 6.43 percent return on the Dow Jones industrial average. In fact, when you factor in expenses, Druker’s 20-month old value-oriented fund did worse than a plain vanilla S&P index fund.

For this they’re paying such high fees?

“We have consistently stressed that our strategy is designed for longer term returns, recognizing there will be fluctuation in the short term,” a “disappointed” Druker wrote in a confidential letter to investors last week, a copy of which has been obtained by The Post.

“Given that it is the general goal to buy low and sell high, it’s getting easier to be buying lower,” he wrote. “Lower prices do not always equate to better values, but so long as we continue our process of investing in companies that are solid, value-based, exhibit strong prospects and have value unlocking potential, we will eventually be able to sell higher.” Richard Wilner

Eli’s on top

As Madison Avenue sharpens its focus on Giants quarterback Eli Manning as a possible uber pitchman should he win the Super Bowl next Sunday, it appears to be one step behind football fans.

Manning has suddenly and unexpectedly become the No. 1 search target on Steiner Sports’ Web site, the result of overwhelming fan interest in the superstar Peyton Manning‘s little brother.

Drawing a level of fan interest usually reserved for the likes of Derek Jeter, Tom Brady and legends like Mickey Mantle, Eli Manning is among the hottest commodities in sports right now at SteinerSports.com.

“He’s blowing them all away,” Kevin Lee, director of e-commerce at Steiner, said of Manning-mania. “During the same football season, I’ve never seen a turnaround like this. Eli was always a popular search term on the site, but now he is THE guy.” Richard Wilner

Hot ads

If you’re not the kind to bet on the Super Bowl, here’s a stock-picking tip courtesy of the University of Wisconsin at Eau Claire: buy shares of Coca-Cola, Toyota, Dell, Pepsi, Anheuser- Busch, Bridgestone, Under Armour and Hershey.

These companies all plan to air spots during the much- watched Super Bowl telecast next Sunday and, according to the brainiacs at UWEC, in 10 of the last 12 years, the aggregate stock price of companies that ran in- game ads beat the S&P 500 during the two- week period extending seven days each side of the game.

Put another way, if you bought every publicly traded Super Bowl stock in the last 12 years on the Monday before the game and then sold it five days after the game, you would have outperformed the S&P 500 by 1.3 percent. Holly M. Sanders

We wuz robbed

Christie’s says it got robbed of the world title. The auction house is smarting over the way Bloomberg News – by the flick of a key stroke – snatched away its title and awarded it to rival auction house Sotheby’s.

The trouble started when Christie’s announced it captured a record $6.3 billion selling art treasures in 2007. Bloomberg News reported the event but calculated the total using a recent and weaker value of the greenback, thus lowering the sales to $6.1 billion.

Meanwhile, Sotheby’s immediately shot out a statement that its sales were $6.2 billion, beating Christie’s by a nose, which Bloomberg reported, using a value in 2007 dollars and declaring Sotheby’s the winner.

Christie’s returned fire this week in hopes of setting the record straight. Paul Tharp

Nets go green

The New Jersey Nets may not be able to win a game – they lost seven in a row going into the weekend to fall into ninth place in the East, out of a play off position – but they are certainly in first place in the race to save the planet.

The soon-to-be Boys of Brooklyn are shooting to become the first team in the NBA to become carbon neutral.

Initiatives, the team’s special NetsGoGreen Web site trumpets, will include improving energy efficiency, raising recycling rates, water efficiency, indoor environmental quality, and establishing green pro curement policies for the Nets to use on a regular basis, such as paper and cleaning supplies.

Superstar Vince Carter is so excited about the initiative he is said to be recycling several moves to the hoop from seasons past. Richard Wilner

Drink up

Happy days are here again – at least in the eyes of Bear Stearns chief economist David Malpass.

“The Fed has glued together the punch bowl of excess liquidity,” Malpass wrote in a memo last week after the Fed’s 75 basis point rate cut.

“It was shattered in August 2007 with the breakdown of the securitization process. The 75 basis point inter-meeting rate cut on Jan. 22, with the prospect of another 50 basis points on Jan. 30, should act as a reset button, mobilizing the reservoirs of existing liquidity and recreating the ultra-liquid investment climate of earlier in the dec ade.” Richard Wilner

business@nypost.com