“What if you could see the prices of the stocks you’re following only once a day, but other investors following the same stocks could see the prices as they changed?” Philip Elmer-DeWitt asks for Fortune. “That, in broad strokes, was the situation from 2007 (when the Securities Exchange Commission created a national market system) until last Monday, Dec. 9, when NASDAQ and the NYSE began reporting small trades of less than 100 shares to the “consolidated tape” — the stream of prices visible to the public.”
“That might seem like a minor change, and for most stocks it probably is,” P.E.D. reports. “But for a high-priced stock like Apple (AAPL), which was selling in lots of 100 for more than $56,000 Monday, odd lots are a very big deal. Most investors can’t afford to drop $56,000 in a single trade. According Nanex CEO Eric Hunsader, 45% of all trades in Apple are in lots of less than 100 shares, and therefore invisible to the public under the old regime… ‘Several things will happen,’ says Namex’s Hunsader, a critic of high-frequency trading. ‘First, games that used to rely on that asymmetric information will no longer work. That in itself is good, with no effort on the part of the investor. Second, it will allow retail applications to better detect the supply/demand picture, etc. By knowing where these odd-lot trades are executing for example.'”
Read more, and see the chart, in the full article here.