Russia's currency hit a new all-time low, due partly to the drop in the price of oil, its major export. The ruble's 12 percent fall on Dec. 15 alone was its biggest daily loss since the 1998 crisis. And oil's slide accelerated, taking Brent crude down almost 50 percent since June to a fresh five-year low.
In the week ending Dec. 12, the S&P fell 3.5 percent, breaking a run of seven weekly gains and recording its biggest weekly loss since May 2012.
"It's very unsettling. The market shouldn't be doing this. It's almost got an air of 2007-2008 about it," said Mark Ward, head of execution at Sanlam Securities in London. "The Dow shouldn't be rallying 400 points, the biggest rally in years. The news isn't good enough to see the rallies we're having and the news isn't bad enough to see the sell-offs we're getting."
Volatility Here To Stay
The roller-coaster ride of the last few weeks may be an indication of what's to come if similar periods of volatility in recent history are any guide, said Ashraf Laidi, head of global strategy at City Index in London.
Before the bull runs in the S&P from 1995 to 1999 and from 2003 to 2007 ended, investors also faced wrenching price moves.
Laidi noted that the S&P has risen for seven consecutive weeks on nine previous occasions, but never in those cases did the index fall more than 2 percent in the week that ended the winning streak. The S&P's 3.5 percent fall in the week ending Dec. 12 "shows an unprecedented departure in sentiment from greed to fear," he said.
That fear, however, should not prevent the rally continuing as long as economic growth and easy monetary policy around the world underpins corporate earnings and profitability.
Investors have been through this before. In the past strategists, worried about the longevity of the rally and global economic signals, have said it's time stocks took a break, only to see them rocket higher in the months that followed.
Investors wary of missing out on what could be a late-stage bull market have been jumping in, quickly seeking bargains after two near-corrections in the last three months.