how many shares in a board lot

Sensei answered 5 months ago …

Wow, I didn't think anyone used this term anymore. The answer is 100. Back in "the olden days", if you wanted to buy stock "at the market", you had to do so in 100 share lots.

Brokers referred to lots of less than 100 as "odd lots". If you wanted a quantity of stock that wasn't divisible by 100, you had to give the market maker "discretion", which usually meant that you'd have to pay 1/8 or 1/4 of a point more than the quoted "ask" for the odd amount.

The situation today is much different. First, computerization of the market means that the supposed difficulty in handling lots of less than 100 no longer exists so the issue of "discretion" doesn't matter. The market maker isn't concerned about how he's going to get rid of the difference between 100 shares and what he has to buy from or sell to you. And second, the market no longer moves in increments of 1/8 of a dollar (12.5 cents.) It moves in pennies. Even a stock like Google that trades in the hundreds of dollars a share is quoted to the penny.

Still, the remnants of "board lots" hasn't completely disappeared. Most investors still buy shares in 100 unit quantities. And it is likely also the reason that option contracts are for 100 shares of the underlying stock.