As an indication that weaker U.S. growth is an issue, look at Transports. Airlines were down 2 to 3 percent on Ebola concerns, but truckers and railroads were down 2 percent as well. That's a sign slower U.S. growth is a factor in the drop.
Ebola concerns are definitely an issue. Healthcare facilities --particularly big hospitals like Universal Health Services, Tenet Healthcare and Lifepoint Hospitals--were all down 4 or 5 percent.
Oil threatening to break below $80 for the first time since 2012 again weighed on energy stocks...big exploration and production names like Apache (APA) and Chesapeake (CHK) were down 2 to 4 percent, as were refiners like Valero (VLO) because gasoline prices have been dropping as well.
As for M&A, the apparent demise of the Abbvie-Shire deal is another headache for hedge funds, who were heavily invested in the $54-billion deal.
That has nothing to do with economic data at all: tech and healthcare have been the beneficiaries of these tax inversion deals, so many of the deals built around tax strategies to grow earnings may be going by the wayside.
This whole push-back on tax inversions and sweetheart tax deals is not as much of a sideshow as it might seem. Interestingly, big brewers like Molson Coors (TAP), down 4.8 percent, and Craft Brew Alliance (BREW), down 6 percent, have been part of speculation of big mergers might happen.
Still, the trading action has been encouraging. Several times today, there has been strong volume push to the upside on market bottoms: at 9:44 AM ET and roughly 1:30 PM ET. During these periods, ETFs used by active traders like the PowerShares QQQ Trust (QQQ), iShares Core S&P 500 (IVV) and iShares Russell 2000 (IWM) saw notable volume spikes.