William Ackman, Director at Chipotle Mexican Grill (NYSE:CMG), made a large insider buy on September 7, according to a new SEC filing.

What Happened: A Form 4 filing from the U.S. Securities and Exchange Commission on Tuesday showed that Ackman purchased 41,208 shares of Chipotle Mexican Grill at a price of $1910.2 per share. The total transaction amounted to $78,710,345.

They now own a total of 1,114,725 of Chipotle Mexican Grill worth, 2,126,683,502.

Chipotle Mexican Grill shares were up at $1907.81 after Wednesday's closing.

The Importance of Insider Transactions

Insider transactions shouldn't be used primarily to make an investing decision, however, they can be an important factor for an investor to consider.

In legal terms, an "insider" refers to any shareholder who owns at least 10% of a company. This can include executives in the c-suite and large hedge funds. These insiders are required to let the public know of their transactions via a Form 4 filing, which must be filed within two business days of the transaction.

When a company insider makes a new purchase, that is an indication that they expect the stock to rise.

Insider sells, on the other hand, can be made for a variety of reasons, and may not necessarily mean that the seller thinks the stock will go down.

Transaction Codes To Focus On

Check Out The Full List Of Chipotle Mexican Grill's Insider Trades.