By Meena Krishnamsetty

NEW YORK ( Insider Monkey) -- Greenlight Capital's David Einhorn has the ability to move stocks.

Last week, Insider Monkey interviewed Einhorn about his book, Fooling Some of the People All of the Time.

We also asked him what was his favorite stock for 2011 , and he replied that it was Dutch insurer Delta Lloyd (DL:Euronext).

"That's probably the only stock we have that I think can double and it would still be cheap," said Einhorn.

Insider Monkey is a new finance blog, so we were quite excited to learn of David Einhorn's extremely bullish views about this obscure Dutch stock. Our article was picked by several Dutch Web sites within a couple of hours, and Delta Lloyd stock started its climb. The first day (Jan. 4), it went up by 3.2%, followed by a 4.8% increase the second day, and a 2.5% increase the third day. In three days the stock gained more than 10% and has been trading around those levels since.

David Einhorn's endorsement increased the market value of this stock by more than $325 million. Bruce Berkowitz was talking about sending Einhorn a box of chocolates after his presentation about St. Joe ( JOE). We think Aviva ( AV), which owns 57.6% of Delta Lloyd, and other investors of the company should take note. David Einhorn's Greenlight Capital owns between 5% and 10% of the Dutch insurer, so Greenlight had more than $17 million of paper profits in three days.

This isn't a pump-and-dump scheme in a penny stock. It's public knowledge that David Einhorn owns at least 5% of Delta Lloyd, according to a filing made on May 7, 2010 in the Netherlands. Last year he shared this information with investors in one of his investor letters as well.

Investors have two things to learn from this story. First, they should follow David Einhorn's comments because those comments can affect stock prices. Second, the Efficient Market Hypothesis is a huge lie. It took Delta Lloyd stock three days to digest Einhorn's endorsement. It is not true that "markets are so efficient that they instantaneously reflect new information."

This article was originally published at Insider Monkey.
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