It might easily be various funds locking in huge gains as they do every year at this time. If so, they will buy back the same stocks next year.
Speaking of panic, early in my career I was working on a time sensitive high visibility project. My boss came by and asked how I was doing and if he should panic. I turned to face him, squinted one eye closed and considered. After a full minute I said, “Yeah, go ahead and panic. You shouldn’t leave it to too late.”