Thanks for all of the replies.
His teacher has tried to let him earn his way back up a color a few times, but it has rarely worked.
I did hear back from his teacher this morning. We are thinking about moving him to his own spot, alone. She has moved him all over the classroom and he always manages to find a "buddy" as she put it. We had the same thing happen last year around this time of year. In Kindergarten, we talked his teacher out of moving him, talked to him at home about that possibility, and his behavior improved.
She also said that he does not do his classwork most of the time unless she is standing there making sure he is doing it. However, when it comes to tests, he breezes through them and get almost everything correct. I asked her if she thought that maybe he needed more work in class.
We have tried various rewards. He can get video games for the weekend if he gets more greens than yellow in a week (no reds) so we aren't trying to make him perfect. Several times, after a bad few days, I'll tell him we'll stop for an Icee after school if he gets green that day. If he gets all green for the week, we plan something extra fun for the weekend, just for him.
He is an only child, but please don't blame his behavior on that. I am an only child and never acted this way. He plays with lots of kids all of the time, including his cousins and he plays some type of team sport throughout the year. Plus, we've been trying to have another child for over 3 years and have gone through various infertility tests and procedures with no luck. Please do not blame this on my inability to give my son a sibling. If you haven't been there, you don't know what it is like. And if you have been there, you know that hearing this type of comment puts you over the edge. I don't buy into that "only child" stuff.
Today is a good behavior party and he cannot go because he received more than 4 reds this 9-weeks. Hopefully sitting out this party will make some of this sink in a bit for him.