Technically, it's unknowable. Most times, you can expect it to be about what it was 5 seconds before. Out of the total number of regular trading hours in the

Technically, it's unknowable. Most times, you can expect it to be about what it was 5 seconds before. Out of the total number of regular trading hours in the year, in how many seconds are major ETFs transacting outside 1% above or below a quote from 5 seconds earlier? How about when you exclude periods in which the market is volatile in a newsworthy way?