Stock market volatility is back, a signal to some experts that the powerful rally that started in early March may be coming to an end.

The Dow Jones industrial average rose or fell more than 100 points in seven of the past 12 trading days, capped by a 205-point advance on Thursday that left the index almost 53 percent higher than its closing level on March 9.

The Dow's muted 17-point gain on Friday masked the fact that it swung nearly 108 points throughout the day after the government reported the unemployment rate rose to 10.2 percent in October.