Originally Posted by prometa

Volatile pricing close in isn't that unusual, especially on lighter loads. (On tight loads it's basically C and M fares all the way to the gate). Have you looked at what buckets are selling? If you have like S4T2L1 or similar and then a group of 4 buys tickets, you might end up on a much higher fare class until more inventory opens. I've also recently seen UA fares jump close in as an AP window closes, only for RM to open up new cheaper fares a day or two later if the flight is very empty.