Twenty percent. That's how much a given index must rise above its previous bear market low for a new bull market to begin.

The S&P 500 is tantalizingly close to that magic level. The highly followed index reached its low point on Oct. 12, 2022. It's now up just a hair below 20%.

A new S&P 500 bull market is nearly here. And there are three no-brainer stocks to buy sooner rather than later.

1. Amazon

Amazon (AMZN -3.05%) is already in a strong bull market of its own. Its shares bottomed out on Dec. 28, 2022, and have now skyrocketed more than 50% higher. Amazon should have plenty of room to run.

Investors haven't really seen the impact of Amazon's streamlining yet. The company's management is focusing heavily on boosting profits. They've shut down underperforming business units and reduced headcount. These efforts will generate higher earnings and free cash flow over time.

A roaring S&P 500 would likely mean that the U.S. economy isn't entering a recession. That would be great news for Amazon's business across the board.

Arguably the most important reason to buy Amazon, though, is the long-term prospects for its cloud hosting unit. Amazon Web Services ranks as the biggest player in the cloud. It could deliver massive growth, especially as the rapid adoption of AI spurs organizations to move to the cloud.

2. Berkshire Hathaway

Like Amazon, Berkshire Hathaway (BRK.A -0.44%) (BRK.B -0.45%) stock has already entered bull market territory. Shares of the giant conglomerate are up close to 25% since reaching a low on Oct. 12, 2022.

Warren Buffett wrote to Berkshire Hathaway shareholders earlier this year that the company is "more broadly aligned with the country's economic future than is the case at any other U.S. company." I think he's right.

Berkshire operates a railroad, a big energy provider, a huge insurance business, manufacturing companies, and more. It's the largest shareholder in eight major American companies: American Express, Bank of America, Chevron, Coca-Cola, HP, Moody's, Occidental Petroleum, and Paramount Global.

There's arguably no single stock that gives investors exposure to as many sectors as Berkshire. If the U.S. economy booms, so will the S&P 500. And so will Berkshire Hathaway. 

3. Vertex Pharmaceuticals

Some biotech stocks have floundered despite the improving overall market. Others have flourished. You can put Vertex Pharmaceuticals (VRTX -1.62%) firmly in the latter category. Its shares soared nearly 32% last year and are up around 16% so far in 2023.

Vertex thinks it could have five launches on the way in the next five years. It's already awaiting regulatory approvals for exa-cel in treating sickle cell disease and transfusion-dependent beta-thalassemia.

The company expects to wrap up late-stage studies of a triple-drug combo targeting cystic fibrosis (CF) by the end of this year. Late-stage studies evaluating non-opioid pain drug VX-548 should complete around the same time. Assuming those results are positive, Vertex will likely file for approvals of both products next year.

All of the big biotech's late-stage products have blockbuster potential. In the meantime, Vertex continues to enjoy a monopoly in treating the underlying cause of CF. This CF franchise has enabled the company to build up a big cash stockpile that allows it to invest in expanding its pipeline even further.