This may be helpful to some who follow the stock market, and especially if you have an account with Charles Schwab or the former T.D. Ameritrade. I'm speaking from the standpoint of Schwab, as that's where I do business. Also, I worked there almost 20 years (until 2017). Ok, now that's out of the way...
Traditionally, a Good til Cancelled order was a way to have an order on the books for more than just the day you are placing a trade. For instance, let's say a stock is currently $50 a share. You like the stock, but don't want to pay more than, say, $45.06 for it. (I like being just above round numbers when buying and below them when selling- this is like taking cuts in line without anyone being able to shout out- "Hey, that's not right!")
The odds are that the stock isn't going from $50 to $45ish in a day. So you decide to leave your order as a Good til Cancelled order, where it will be on the books for 60 days. I've used GTC orders many thousands of times over the years. They do require that you keep focus on your open orders so that, for instance, too many of them don't cause you to spend more than you really want to spend.
Now GTC orders have changed at Schwab (and perhaps elsewhere) in at least THREE MEANINGFUL WAYS recently:
1) GTC orders are now good for up to 180 days instead of just 60 days. This, in and of itself, is fantastic IMHO.
2) Taking things one step further, a GTC order to buy or sell can be tailored to a specific day. Here is an example. I would like to participate in a coming tender offer, but will only consider buying the stock at a lower price for the next, say, 22 days while the tender offer is still active. I can tailor my buy order to be open for only 22 days. I literally called Schwab last night to recommend that they add this capability to the orders for a specific trade I was doing, and the rep said "We already have it". I was shocked and super pleased to say the least!
3) This last one is absolutely HUGE for me and it is the fact that you can have a GTC order be active for the regular session or you can have it be active for extended hours (both pre-market and after hours) plus the regular session. I've had so many times in the past that I had an order to buy (or sell or short) a stock during the regular session. Then, it would trade at my price in extended hours, yet my order wouldn't be filled. That's because they were different venues and didn't cooperate with each other on order execution. Not anymore! The amount of time I save by not having to re-enter orders over and over day after day (sometimes 3 times a day for the same stock in pre-market, the regular session and after hours) is incredible.
God bless America! Can you imagine being in some foreign country with maybe 50-100 stocks total to trade any only a handful of real companies. We are so fortunate here.
One small request- if you have an account (especially outside Schwab), please let me know what you've found about the changes to GTC orders. If you are with Schwab and know of some other change that I'm not aware of, please chime in as well. Thanks in advance.