Now that I am thinking about it, I can name at least one that I am sure is worse than any listed:
Jaws 2 ... WAAAAYYYYY worse than Jaws. Almost incomparably so.
Also, National Treasure 2 was pretty bad. I liked the first one quite a bit, but the second is poor.
Ah, what the heck, might as well throw another on... and probably the worst of them all: Â Indiana Jones and the Kingdom of the Crystal Skull. Â GOD AWFUL. Should never, EVER have been made.
And now that I think about it, and a few people have mentioned it, why is ST:TMP on this list? It is not a sequel. Unless you consider it a sequel to the show, which is not a very fair comparison if you ask me.
Jaws II came to mind.