"the SIP price of Apple stock & the price seen by traders w/ faster market information differed 55,000 times in a day." #readingToday

In a paper published in February 2013, a team of researchers at the University of California, Berkeley, showed that the SIP price of Apple stock and the price seen by traders with faster channels of market information differed 55,000 times in a single day. That meant that there were 55,000 times a day a high-frequency trader could exploit the SIP-generated ignorance of the wider market. Fifty-five thousand times a day, he might buy Apple shares at an outdated price, then turn around and sell them at the new, higher price, exploiting the ignorance of the slower-footed investor on either end of his trades. And that was only the most obvious way a high-frequency trader might use his advance view of the market to make money.

Flash Boys Michael Lewis