Here we go again. Market volatility is picking up, and it's causing an upset stomach for many an investor.

There is an excellent remedy, though — tilt the equity portion of your portfolio toward large, high-quality companies that provide essential products and services and pay strong dividends. Shares of these companies typically display well-below-average price volatility because investors can count on them, so a painful sell-off is much less likely in rough markets.

True, these stocks tend to be well beyond the fast growth phase, but you'd be surprised at how many manage to pace or outperform the overall market over time, which is a notoriously hard thing to do.

To find such a stock, you need only scan a list of the 30 companies that make up the Dow Jones Industrial Average. The one I'd like to tell you about currently pays a dividend of $ 1.76 a share, which translates to a very attractive yield of just under 6% based on recent share prices.

And talk about a stock that helps you sleep better at night… The price tends be much more stable than average, typically fluctuating only about half as much as the overall stock market. You can tell this from the beta coefficient, a simple statistic that compares a stock's price movement to that of the market. If the beta is 1.0, it means the stock moves with the market. The Dow stock I'm referring to — AT&T Inc. (NYSE: T) — has a beta of 0.46, so it's usually 54% less volatile than the market.

For those of you worried about AT&T's ability to compete and pay high dividends after last December's decision to abandon a $ 39-billion deal to acquire 4G wireless provider T-Mobile USA Inc., don't let the setback deter you from owning this safe, high-quality stock. Yes, owning T-Mobile would have contributed greatly to AT&T's profit-making ability if the government hadn't foiled the deal with an antitrust lawsuit. But the fact is AT&T will be just fine without T-Mobile.