Traders are sticking to a losing bet that a placid stretch for stocks is coming to an end.

The CBOE Volatility Index, or VIX, an options-based measure of expected stock-market swings, last week hit its lowest level since 2007. The Dow Jones Industrial Average has gone 32 months without a 10% decline, the fifth-longest run on record. The S&P 500 hasn't closed up or down 1% in 46 days, the longest stretch since 1995.