"Chipotle is in the very early stages of beginning to realize its potential," the fund manager told Reuters on Friday, adding that he "loves" the stock.

Ackman spoke one day after his Pershing Square Capital Management hedge fund said in a regulatory filing that the firm had cut its holding in Chipotle to 7.4 percent of the company from 10.4 percent. His firm sold 823,357 shares for portfolio management purposes, the fund manager said.

He said the Chipotle position had grown to be more than 20 percent of his roughly $8 billion portfolio as the stock price appreciated and that it needed to be cut back. He has periodically trimmed positions as they became too big.

News of the sale came after the market closed on Thursday and sparked some concerns on Friday that Ackman was possibly losing interest in the company after owning it for almost two years.

Ackman has helped turn the company around, playing a big role in wooing Chipotle's new Chief Executive Officer Brian Niccol from Taco Bell.

Since Niccol took over in March, the stock has gained 92 percent through Thursday's close of $483.99.

On Friday the stock lost 1.74 percent to trade at $475.55 late in the session.

Ackman's hedge funds have gained roughly 15 percent so far this year, beating the average hedge fund, which lost roughly half a percent, according to data from Hedge Fund Research.

(Reporting by Svea Herbst-Bayliss; Editing by Dan Grebler)