Marvel Entertainment (MVL, $35.18, up $1.31) is trading higher today after Standard & Poor’s said the company will soon replace insurer The Commerce Group in the S&P MidCap 400 index which is being acquired by Mapfre. No date of the change has been set.

In after-hours trading last night, Marvel shares were up $1.02 and have extended those gains as fund managers snap up shares. Whenever a stock is added to an index, mutual fund managers must buy the shares to represent the stock that is being added.

Marvel has been on a roll and was at $32 when I mentioned it a month ago after the release of its earnings and Iron Man. The Incredible Hulk is set to open on June 13 and could see some big numbers following Iron Man’s $400 million take so far. Iron Man’s success is evident in the popularity of Marvel’s characters and although the first Hulk was a dud, this one is getting good reviews.

The June 35 calls (MVLFG, $1.45, up $0.65) are up 80% as they moved in-the-money with today’s big move in the stock. The July 35 calls (MVLGG, $2.08, up $0.78) are up 60% and could have further room to run if Marvel continues to set new 52-week highs.

Rick Rouse