On any given security with options, the "highest gamma expiration date" is the market day for which the largest amount of positive market gamma expires. You can sort for these highest gamma expiration dates in our Equity Hub™.

Market maker activity tends to build as this date approaches, adding even more positive gamma. Usually, this date will be on a monthly options expiration, but sometimes it can be tied to earnings or major economic events. There is a tendency for the underlying security to pin (stick) to large gamma strikes as it gets closer to a large expiration date, which means staying in a tight range (mostly because of the presence of strongly positive market gamma).