When it comes to the stock market, winners tend to keep winning. That's a core tenet that many investors at The Motley Fool ascribe to. Here are two proven wealth-builders that should continue to deliver handsome gains to their shareholders for many years to come.

1. Berkshire Hathaway

Warren Buffett's Berkshire Hathaway (BRK.A -0.39%) (BRK.B -0.56%) is built to last. The $885 billion investment conglomerate has generated fortune-building returns for its shareowners for decades, and plenty of gains still lie ahead.

Berkshire owns more than 60 subsidiaries operating in industries as varied as insurance, railroads, homebuilding, and restaurants. GEICO Auto Insurance, BNSF Railway, Clayton Homes, and Dairy Queen are among Berkshire's stable of competitively advantaged businesses. Combined, these high-quality companies generated operating earnings of $37.4 billion in 2023.

The diversified revenue streams these companies create help to reduce the risks for Berkshire investors. Combined with its fortress-like balance sheet, which held almost $190 billion worth of cash and other reserves as of March 31, these multiple income sources make Berkshire one of the safest stocks available in the market today.

Berkshire's $375 billion public stock portfolio provides investors with another path to wealth creation. Buffett is one of the best in the world at identifying undervalued assets. His stakes in elite enterprises like Apple and Coca-Cola have netted billions in profits for Berkshire's shareholders. Lately, Buffett has been loading up on innovative oil producer Occidental Petroleum, which looks like it could be his next big long-term winner.

Additionally, Buffett has identified another intriguing bargain as of late: Berkshire's own stock. Berkshire has repurchased tens of billions of dollars worth of its shares in recent years. Buy today, and you'll likely be buying alongside the legendary investor.

2. Eli Lilly

Leaders of fast-growing markets can also create riches for investors. Eli Lilly's (LLY -1.38%) game-changing new weight loss drug has positioned the pharmaceutical giant to claim a sizable portion of an anti-obesity market that is projected to grow to $130 billion annually by 2030, according to Goldman Sachs. And Eli Lilly's shareholders are already profiting from its tantalizing growth potential.

People cite multiple and varied reasons for wanting to lose weight. Some want to improve their appearance. Others know that being overweight is linked to a host of potentially dangerous health conditions, including diabetes and heart disease. Eli Lilly's recently approved drug can potentially help prescribed users shed excess pounds and improve several important health metrics.

The drugmaker's Zepbound treatment is a once-weekly injection that suppresses appetite. Participants in a 72-week clinical study weighing an average of 231 pounds each who received the highest dose of Zepbound lost a stunning 48 pounds, on average.

Along with the weight loss, trial participants who implemented a diet and exercise plan experienced favorable changes in blood pressure and cholesterol. Clinical trials have also demonstrated the ability of tirzepatide, the active ingredient in Zepbound, to help adults with type 2 diabetes better manage their blood glucose levels.

Wall Street thinks these benefits could result in Zepbound becoming the best-selling drug of all time. Eli Lilly's earnings per share, in turn, are expected to increase by 62% annually over the next half-decade.

The healthcare titan's nearly 150-year history is filled with scientific breakthroughs like Zepbound that have helped people be healthier. Invest in Eli Lilly's stock today, and you can claim your share of the profits it earns from its blockbuster medicines and future discoveries.