5 Defense Stocks to Buy to Toughen Up Your Portfolio

Hold on to your hats, brace yourself for an uptick in volatility ... and perhaps give defense stocks a look this October.

Goldman Sachs' equity derivatives strategist John Marshall, in a recent report to clients, writes that, since 1928, volatility has been 25% higher on average during the month of October.

"Not only are earnings day moves rising relative to average daily moves, but October tends to be the quarter with the largest absolute earnings day moves for U.S. stocks," Marshall writes. And it's no coincidence. "We believe it is a critical period for many investors and companies that manage performance to calendar year-end."

How should investors play this potential bout of choppiness? Get defensive - with defense stocks. Aerospace, defense and other companies that have a hand in national security are traditionally more defensive investments. They also offer notably low exposure to Chinese trade war tensions.

Encouragingly, the iShares U.S. Aerospace & Defense ETF () is currently