Volatility can serve to remind investors that stocks are inherently risky.

"That will remind investors that oil company profits are on the rise," he said.

Another crash in the late 80's did less damage, but served to remind investors of the pitfalls.

In 1987, falling prices reminded investors of 1929, and many rushed to exit.

And brokers quickly remind salivating investors that service still counts.

"It's going to remind investors that these companies are going to start throwing off a lot of cash," she said.

But it also reminds investors about how much trouble some energy companies are in.

Necessary to remind investors that most stocks do not double or triple in a year.

Many of them like to remind nervous small investors that the market still has a sizable gain for this year.

But the week's developments reminded investors that takeover deals are still a factor in the marketplace.