So in times like these, it's a great idea to peek into the man's portfolio. What stocks does Buffett own that are worth holding onto through market volatility and beyond? Let's consider two prime candidates: Apple ( AAPL -3.59%) and Mastercard ( MA -0.90%).

US tech billionaires have lost more than $400 billion in wealth so far this year, with Tesla CEO Elon Musk leading the way with a $130 billion drop.

Warren Buffett has a seven-word bit of advice for people during stock market turmoil. United States stocks tanked on April 4, following a sell-off after China retaliated against the U.S.'s newly-announced tariffs. The Dow Jones fell by 2,231 points, or 5.5%, and the S&P 500 dropped 5.97% lower. The tech-heavy Nasdaq Composite fell by 5.82%.