September (Roman month) September (Roman month) September (from Latin "septem", "seven") or mensis September was originally the seventh of ten months on the ancient Roman calendar that began with March ("mensis Martius", "Mars' month"). It had 29 days. After the reforms that resulted in a 12-month year, September became the ninth month, but retained its name. September followed what was originally Sextilis, the "sixth" month, renamed "Augustus" in honor of the first Roman emperor, and preceded October, the "eighth" month that like September retained its numerical name contrary to its position on the calendar. A day was added to September in the mid-40s
Delivery month futures exchanges (such as bonds, short-term interest rates, foreign exchange and US stock indexes) tend to expire quarterly, in March, June, September and December. For financial contracts traded on non-US futures exchanges, the expiration schedule may not be quarterly. This table lists the conventional letter codes used in tickers to specify delivery month: To name a specific contract in a financial futures market, the month code will follow the contract code, and in turn be followed by the year. For example, CLZ3 is the December 2023 NYMEX crude oil contract. CL denotes crude oil (crude light), Z corresponds to the