Why are share prices shown 'delayed'.

Factual Questions
1

Old fart that I am I am constantly watching my retirement portfolio. I am wondering why the stock prices are always delayed 15 or 20 minutes. I know it is an exchange rule but don’t seem to be able to find the reason why.

I used to use this fancy widget called the INET bookviewer which gave real time bids and asks for a given security but that has been shut down and requires a subscription.

Is that it? It is so profit can be made by giving real time to only paying customers?

2

Bingo!

3

It also works with places like brokerages. They pay for a real-time feed for stock quotes. If they could get that from the Internet without payment, the people providing the quotes would go out of business.