Shana Sissel believes headline-driven market sell-offs, like Friday's surrounding President Trump's tariff threat against China, are buying opportunities. Sell-offs tied to sustained economic weakness are a different picture in Shana's book. She highlights ways investors can protect themselves against volatility if those situations occur. She later turns to stock picks in Marvell (MRVL) and Leidos (LDOS) to explain how they can withstand volatility.