As a result of the growth of exchange-traded funds (ETFs), volume in certain smaller stocks has spiked disproportionately. This is due to the fact that, when money flows in and out of ETFs, funds are forced to buy and sell the holdings proportionately. Consequently, more money flows in and out of ETFs than mutual funds because they are so easy to trade (bought and sold through any broker at any time during the day), so ETFs have had a much larger impact on small company stock prices and volumes than mutual funds have had historically. According to a
Wall Street Journal (subscription required)
piece on this issue, when the markets fell during late February, "Between Feb. 22 and Feb. 28, just one ETF, the iShares Russell 2000, reported outflows of $2 billion, whereas major small-stock mutual funds
combined had outflows of only $101 million, according to AMG Data Services." (emphasis mine)
While this is seemingly insignificant beyond the obvious (price and volume increases in some index-held small-cap companies), when you consider the implications of a volume spike, the issue becomes more important. Many technicians (people who trade stocks based on their price and volume patterns) use volume as an indicator of "special knowledge." However, ETF buying is certainly not special knowledge, and it is actually the direct opposite -- "insensitive buying." As a result, one must certainly question the validity of volume spikes as a method of choosing stocks with smaller market capitalizations if they previously had any confidence in the methods of technical analysis.