beware of anyone who tells you to buy or sell a stock.
What you have to ask yourself is "do I think the stock will go up higher if I sell now? Later? How much do I think the movie will adjust to when it opens? Will it adjust higher? Lower?"
These are all questions you may want to consider before you sell (or buy) a stock. Big 'tentpole' movies usually do earn a lot, but you have to look at the price of the stock when it opens and decide if it will adjust up a lot more, a little, or not at all.
If you don't need the $$, then why sell something like HGAM3? If you have a $300M port, you can afford to keep long term openers, and typically over time, they go up in price the closer it gets to opening... NOT always... but most of the time.
When I first started HSX, the big term was PPDM. "price paid doesn't matter." Why? Because if you own Ironman 10 when it was $2/share, and I buy it at $200/share right before it opens - sure you made a lot of money before it opens, but I make JUST AS MUCH as YOU do, if I buy it at $200 and it adjusts up another 20 points... we each make the same amount on the adjust. Yes, you made more holding it for months, but I made just as much as you did when it adusts after opening... does that make sense?
So, you have to decide if you want to take your profits now and sell a stock, or hope the price continues to rise and take more profit later...again, if you have the cash, why sell something early if you think the price will continue to rise?
The only time you MAY want to sell, is right before a movie opens, and you compare the stock price, with what you think it may adjust to...if you think it will adjust UP, then hold it. If you think it may adjust down - then either sell it off, or short it and make $$ when it adjusts lower (don't forget commish)
Good luck!