Why do options have an expiration date?

>>1444538
because time has value.

I'll gladly buy all sorts of call options (american style), valid for an unlimited amount of time off of you. sign me up!

what is a non american style option?

>>1444628
Euro options cannot be exercised early. It gives them much less value because you are then hoping for a perfectly timed play.

>>1444635
Well, to be fair - at least in theory derivatives have legitimate uses other than maximizing your profit while gambling. Mostly talking about hedging here. If you know you need 100 AAPL by the 15th of September you can buy a call option to hedge against steep increases. Then you're not hoping for any kind of play, you just want to minimize your exposure to risks. Exercising the option early doesn't really matter in this scenario.

Of course we've come a long way from actual forward contracts. Next to nobody cares about delivery when it comes to futures and options. They just want to close the position optimally and be paid out...

Btw, there's another layer to the joke - what would a european style option with no expiration date even be? Basically gifted money to the short position...

>>1444538
Check delta over 10 years.
No way

Why? Not really asked myself that question but you can buy (and probably sell) options without expirations; they're called warrants. I've not really looked into them much, I'm just concentrating on learning to trade stocks, options and futures.

>>1444891

Actually, scratch that. After checking them a bit more myself they do have expirations, they can just be much longer time frames. Sometimes up to 15 years.