Imbalance of Orders

The goal of the stock market (or any market, for that matter) is to match buyers and sellers. You want to sell your 50 shares of AAPL. You push a button on your computer. Somewhere in the transom of cyberspace, other computers recognize your desire to sell, find someone else looking to buy 50 shares of AAPL, and match the orders. Eureka! The shares transfer to the other person and you get some cash.

Sometimes, though, there are too many people trying to do one kind of action, and not enough people on the other side. Too many shares trying to get sold, without an equal level of requests on the buy side. Or vice versa.

When that situation comes up, it's known as a "market imbalance." Like a teeter-totter. Except that, on one side, you've got a four-year-old kid with an underdeveloped petuitary gland...and on the other, you've got a sumo wrestler who just came from an extended lunch at Johnny Dancer's Wildly Indulgent Buffet Hut.

Usually, small imbalances are smoothed over by a market maker. These are middle men who dip into their own reserve of shares (or buy extra if the imbalance goes in the other direction) to keep the market liquid. However, if things get way out of whack, trading in the stock (or whatever asset is being traded) might get halted while the market waits for a resolution of the imbalance.