Safety First

What's been driving the market rally in September? A flight to security. This month, the biggest gainers in the S&P 500 include firms focusing on telecommunications services, consumer staples and utilities—so-called safe sectors whose steady dividend payouts have long made them investor favorites when markets are volatile or declining.

These shares typically lag behind major indexes during rallies, in part because they are perceived to offer limited potential gains. But in September, telecom shares are up 3.1 percent, consumer staples are up 1.5 percent and utilities are up 1.5 percent, versus a 0.1 percent increase in the S&P 500.

Meanwhile, many well-known high-flyers have been tumbling. Apple, Amazon.com and Alphabet each has declined at least 3 percent apiece in September, partly reversing double-digit percentage gains for the year. Facebook has declined more than 8 percent this month, adding to its retreat in the second half of this year.