All Or None - AON

The order: 100 shares at $15. All or None (AON).

If your broker can't find 100 shares of whatever stock you want at $15, she buys nothing. You've basically told her to go whole hog or abandon ship. Example: Imagine if Warren Buffett decided to buy 10% of Netflix (yes, it would mean the world was ending, but that's a different story). NFLX stock would almost certainly shoot up a ton.

So let's say his brokers were told that it was an all or none order. If his brokers are able to grab the 10% before anyone gets wind of the deal, Sir Warren ends up with a big chunk of a company stock that's about to go sky-high in price. But if the broker gets about 2.3% and then start hemming and hawing very politely, he's stuck. He either has to pay more for the 7.7% (he wanted to get to 10%—and now that everyone's onto him, those NFLX shares are more expensive) or he can turn around and sell the 2.3% so that he has no part of Netflix.

AON deals are done when an investor has enormous Assets Under Management, and the notion is that, unless he has a huge stake in something, it's not worth it for him to have any stake in it. Hence the AON positioning with brokers.