It's true, tenths of a cent can add up. I just can't imagine making any kind of trading decision based on whether something's trading at 32.152 vs. 32.157. I mean, would you actually change your mind about whether to buy a stock because it's a half cent more or less than what's showing on level 2? I know $50 adds up over time, but when you're trading 10K shares at a time, does the half a penny or so actually affect your trading decision?
I really wish they hadn't gone to tenth of a cent increments. I think it's pretty silly. If you have it in your montage, it can be very confusing. Like the figures above, let's say the 32.152 is the bid, and the 32.157 is the ask, I would look at those two numbers, and look at the last digit on each (the 2 and the 7) and automatically think there was a 5 cent spread, rather than a .5 cent spread. I remember on one stock thinking a 4 cent spread was 40 cents. It can actually break your concentration to have to look at 3 numbers after the decimal. I would prefer to have just 2 digits and rounded off. I mean, come on, we're down to penny spreads, isn't that enough?
Besides, it's all going to come out in the wash. You buy 10K shares and save $50, because someone's offering stock at a half penny less. Then you sell, and a bidder bids a half cent less, so you lose the $50 back. I just can't imagine any individual over time gaining a significant advantage because they were able to trade in tenths of a cent.
