Warren Buffett didn't earn the nickname "the Oracle of Omaha" by making bad decisions. The legendary investor has trounced the market over the long term by selecting winners. 

Wouldn't you love for Buffett to whisper in your ear and tell you what he'd recommend you buy? That's unlikely to happen. However, you can still benefit from his wisdom. Here's Buffett's No. 1 pick for investors right now.

Warren Buffett standing in front of microphones.

Image source: The Motley Fool.

Old advice that's still applicable today

Buffett didn't trumpet any stock as the top pick for investors to buy in his latest letter to Berkshire Hathaway (BRK.A 0.48%) (BRK.B 0.44%) shareholders. As far as I know, he's never done so in the past, either. 

Of course, Buffett would probably be happy if you bought shares of Berkshire itself. And if he had to name one individual stock to buy, it would almost certainly be Berkshire. After all, he runs the company -- and the stock has been his smartest investment ever. However, as much as he loves Berkshire Hathaway stock, it wouldn't be the one pick he'd most likely recommend today. In fact, Buffett wouldn't recommend most investors buy any individual stock.

We know this based on what he wrote to Berkshire Hathaway shareholders in 2014. In that letter, Buffett discussed the investing process that he and his longtime business partner Charlie Munger use. He explained that he and Munger don't pick stocks; they pick businesses. And the only businesses they select to invest in are those that are available at an attractive price relative to earnings projections for at least five years in the future.

After describing this process, though, Buffett acknowledged that most investors don't prioritize studying businesses as he and Munger do. He understood that most investors don't know enough about businesses to project their future earnings. However, Buffett didn't view this as a problem. He stated, "The typical investor doesn't need this skill."

So what did the Oracle of Omaha suggest that most investors do? He warned against trying to pick individual winners. Instead, Buffett recommended that investors "own a cross-section of businesses that in aggregate are bound to do well." This advice from several years ago is still applicable today. 

Buffett's No. 1 pick

That leads us to what Buffett's No. 1 pick would be for most investors right now. He explained in the letter to Berkshire Hathaway shareholders that there's a simple way to follow his advice about buying a cross-section of businesses: Invest in a low-cost S&P 500 index fund.

The S&P 500 includes the 500 largest U.S. companies. There are several good S&P 500 index funds to choose from. However, I think we can pretty easily determine which one Buffett likes the most.

Buffett gave a big hint in the letter, writing, "I suggest Vanguard's." Vanguard has an S&P 500 mutual fund -- Vanguard 500 Index Fund Admiral Shares. But I suspect that Buffett's top pick would instead be the Vanguard 500 Index Fund ETF (VOO 0.79%).

I think the legendary investor would recommend the Vanguard exchange-traded fund (ETF) over the mutual fund for two primary reasons. First, the ETF's expense ratio of 0.03% is slightly lower than the mutual fund's expense ratio of 0.04%. Second, Buffett owns shares of the Vanguard 500 Index Fund ETF in Berkshire's portfolio.

Would Buffett recommend investing now?

There's a strong case to be made that the Vanguard 500 Index Fund ETF would be Buffett's No. 1 pick. But would he advise buying this ETF right now? I think he would.

Sure, there's a lot of economic and market uncertainty. However, Buffett wrote to Berkshire shareholders in 2014 that the best thing for investors to do is "to accumulate shares over a long period and never to sell when the news is bad."

Buffett didn't guarantee that you'd make money, but he came pretty close to doing so. He argued that a person who buys and holds a low-cost S&P 500 index fund over the long term "is virtually certain to get satisfactory results." This endorsement from one of the greatest investors ever is one you don't want to ignore.