If you re feeling stock-market whiplash, you aren t alone.

Volatility has made a comeback in recent days. On Friday, the Dow Jones Industrial Average closed at 9,713, down 250 points. That came on the heels of a rally Thursday, which followed a slump on the way down from 10,000 at the beginning of the week. On Friday, the Chicago Board Options Exchange Volatility Index, the VIX, hit 30.69 -- its highest level since July. So what s spooking traders?

For starters, look to the dollar, say some market watchers. The market now is rising and falling in inverse relationship to the dollar, says Jamie Cox, managing partner of Harris Financial Group. The current low interest rates in the U.S. encourage traders to borrow dollars and use that cheap money to finance low-risk investments abroad, says Frank Ingarra, portfolio manager at Hennessy Funds. If those traders start to see signs of volatility in the market, they know investors will be fleeing to the safety of the dollar, so they rush to exit their trades before the dollar climbs too high, Ingarra says.

This strong inverse relationship between the market and the dollar won t last, Ingarra says. As we start seeing more of a bottom in the economy and better potential for the Fed to raise interest rates, they should start decoupling, he says.

Friday s selloff may ramp up investor fears about a coming correction but that correction may already be underway, Cox says. Broadly speaking, the economic data looks good, but the market doesn t seem to be encouraged by signs of recovery, he says. We are deep in the throes of a correction, and I think we will exit it soon, Cox says.

So how much fright should you feel this Halloween weekend? Depends on your time frame, some would argue. The market is in a skeptical stage, but the long-term trends are good, says Tommy Williams, president of Williams Financial Advisors. Long-term investors don t need to worry about measures of short-term activity like the volatility index, as long as they have a sell discipline in place, Williams says. Rather than reacting to a single day s events, when you ve made some money, you sell, and protect your profits, he says.