Father Knows Best: Carl Icahn edition

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Carl Icahn's Netflix investment may be the most annoying Best Trade Ever.

Last fall, Icahn revealed that he had bought a 10 percent stake in Netflix. His average price per share was around $58 each.

Back on Oct. 10, Icahn started selling shares. The biggest sale took place Tuesday, when he sold for an average price of just over $344, for a total of $819 million. That means he made a profit of about $645 million on Tuesday's sale alone.

All told, his profit for the fourteen month investment was between $700 and $800 million.

And he still owns about half of his original stake.

(Read more: Traders debate Icahn's Netflix move)

What makes this all so annoying is that it didn't involve any fancy financial engineering.

John Paulson made a fortune shorting the mortgage market by getting firms like Goldman Sachs to sell complex derivatives to unsuspecting large investors. Venture capitalists make fortunes by finding companies like Twitter and pouring money in at early stages. Warren Buffett can get Goldman to sell him pricey warrants that pay off grandly.

These aren't really trades available to ordinary mortals.

But Netflix was.

Icahn bought the common shares that any other mortal could have bought. And he made a killing.

It only makes it worse that you didn't even have to outsmart Icahn or somehow front-run his trade to make money on this trade. You only had to follow Icahn to earn the kind of return that you could brag to your children about. In other words, this is something you could have done but almost certainly did not.

If it helps you out, I'll remind you that we only know this with hindsight. Many people thought Icahn was out of his mind to buy that stake in Netflix last fall. Smart investors don't try to pick stocks. Even if they sometimes pick a winner, most investors will lose money stock picking.

What's more, if you just stayed in your usual diversified portfolio of stocks over the past 14 months, you've done really well. Just not as well as Carl Icahn.

Amazingly, the co-managers of the portfolio at Icahn Enterprises L.P. wanted to stay in the trade.

"Our cost basis in Netflix is $58 per share. Despite its notable appreciation in just over one year to $323 per share...we believe the company remains significantly undervalued," they wrote in a statement yesterday.

By the way, the co-managers are David Schechter and Brett Icahn, Carl's son.

But at Icahn Enterprises just being named Icahn isn't enough. Carl calls the shots. And Carl knows a good thing when he sees it. It was time to sell half the stake.

"While I basically agree with David and Brett's assessment...and have often held positions for many years, as a hardened veteran of seven bear markets I have learned that when you are lucky and/or smart enough to have made a total return of 457 percent in only 14 months it is time to take some of the chips off the table," Carl responded.

Father knows best.

(And so did Jim Cramer, who called it a "Generational buy.")

But David and Brett probably aren't all that upset that Papa Icahn overruled their Netflix addiction. Their agreement with the company means, apparently, that if Netflix keeps going up, they'll earn bigger bonuses.

"In order to address certain provisions under the Co-Manager Agreements, Carl Icahn and Icahn Enterprises reached an agreement with David Schechter and Brett Icahn...that will allow Carl Icahn and Icahn Enterprises to reduce their exposure to Netflix while allowing the Co-Managers to maintain the potential to receive compensation under the Co-Manager Agreements based on the performance of Netflix shares," the statement from Icahn Enterprises explained.

—By CNBC's John Carney. Follow him on Twitter @Carney