In 2006 Cboe introduced Quarterlys -- options that expire at the end of calendar-year quarters (March, June, September and December).
In 2014 Cboe introduced PM-settled, End-of-Month options series (EOM) -- with expiration dates falling on the last business day of the month -- for its S&P 500® Index (SPXSM) options. Cboe added SPX EOM options to its SPX options product line in response to requests from asset managers who want to more precisely match SPX option expirations to end-of-month fund cycles and fund performance periods.