Settlement Period for options pre 1993

External question — Personal Finance Stack Exchange Author: puzzled Original post: https://money.stackexchange.com/questions/120898 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I was reading Settlement Period and wondering what was the settlement duration for options pre 1993. For equity/etf, it seems it was five days. So for options, was it four days ? , any verifiable link will be appreciated. Note: I understand that for stocks now it is T+2 and for options it is T+1. per link : Most security transactions, including stocks, bonds, municipal securities, mutual funds traded through a broker, and limited partnerships that trade on an exchange, must settle in three days. Government securities and stock options settle on the next business day following the trade. and another link : 7 Settlement in the futures, options , and government securities markets occurs on the day after trade date ("T+1") using same-day funds. Settlement of most trades in corporate and municipal securities, on the other hand, takes place on the fifth business day after the trade date ("T+5") with money payments among financial intermediaries made in next-day funds (i.e., payment by means of certified checks passing between the clearing corporation and its members). So, it seems for Futures and options it has been always T+1, irrespective of what is settlement in Equity market... Any one who has been in investment for long, can please verify ?