Stocks have had a historically rough start to the year, with the S&P 500 (INDEX: .SPX) falling 6 percent for its worst week of losses since 2011. But despite the rocky road, one director of asset allocation says stocks should still play a large role in an investor's portfolio.

"For a 40-year-old investor right now, he or she should have at least a minimum of 80 percent in equities right now," said Albert Brenner of People's United Bank Wealth Management on Friday's " Power Lunch ."

"I know that seems crazy after the four days we've had at the start of this year, but that's what the minimum would be."

The S&P 500 has lost nearly $1.1 trillion in market cap in the first week of January. For investors looking to protect their investments, Stacey Gilbert, head of derivatives strategy at Susquehanna, recommends buying put options on the S&P 500 ETF, SPY (NYSE Arca: SPY). Put options are a contract to sell a specific security at a set price and a set date.

However, Gilbert warned that the prices on protective options have risen amid the week's stock sell-off.

Read More With stocks tanking, should investors dash to cash?

"On a relative basis just given the recent volatility in the marketplace, those puts are trading more expensively than they have been," Gilbert said Friday, also on "Power Lunch." To account for the higher prices on options, Gilbert recommends using another options strategy called a risk reversal, in which one buys a put option and sells a call option, which limits profits but reduces the cost of buying.

"We have seen investors buy puts for protection, a very common strategy, and they sell some of the upside calls against it to help finance those downside puts that they're buying," she said.

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