Watch Art Cashin: Why stocks are getting slammed

Cashin says we're living in 5-year paradox

Art Cashin said stocks are down today amid fears the economy isn't growing fast enough to support the growth we've already seen in equity prices as they've hit all-time highs.

Cashin, UBS' director of floor operations at the NYSE, told CNBC's Bob Pisani around midday, "We're living in a five-year paradox here. Things like GDP, the macro numbers, have not lived up to what the market was doing. And the market has done what it's done simply on earnings. And through financial engineering we've gotten the earnings up."

His concern: "What about the top line? You can't grow revenues, particularly if GDP is not going to move. So suddenly the macro is going to matter. And that could be a problem."

Read MoreTepper on the market: 'Don't be too fricking long'

Cashin said traders are also worried the European Central Bank does not have the ammunition it will need to counter expected economic weakness, particularly in the "periphery" of the continent, this summer.

He also sees "deflation breaking out" as bond yields fall around the globe.

Read MoreStocks in the red as bonds catch fire

—By CNBC's Alex Crippen. Follow him on Twitter @alexcrippen.