Investing doesn't have to be complicated. You can make a lot of money in the stock market by simply buying and holding the best businesses in the fastest-growing industries.

These two companies are leaders in rapidly expanding markets -- and their stocks are both well-positioned to deliver fortune-building gains to their shareholders in the years ahead.

1. Nvidia

Artificial intelligence (AI) is set to reshape the global economy. That's not hyperbole. But I won't ask you to take my word for it. Listen to what Microsoft co-founder Bill Gates had to say about this game-changing technology:

The development of AI is as fundamental as the creation of the microprocessor, the personal computer, the Internet, and the mobile phone. It will change the way people work, learn, travel, get healthcare, and communicate with each other. Entire industries will reorient around it. Businesses will distinguish themselves by how well they use it.

Perhaps no business is set to profit from this megatrend more than Nvidia (NVDA 0.03%). The semiconductor titan designs the bleeding-edge chips that power the most advanced AI applications. Its sales, in turn, are booming.

Nvidia's revenue soared 206% year over year to $18 billion in the quarter ended Oct. 29. Meanwhile, its adjusted earnings per share skyrocketed 588% to $10 billion. That's a staggering level of growth for a $1.2 trillion behemoth.

Yet Nvidia has a long runway for expansion still ahead. The AI chip market alone could reach $400 billion by 2027, according to some estimates. When factoring in other lucrative opportunities in gaming, autonomous machines, and cloud services, Nvidia pegs its total addressable market at a staggering $1 trillion.

With so much growth still to come for this technological marvel, investors who buy Nvidia's shares today should be well rewarded.

2. Tesla

The rapid expansion of the electric vehicle (EV) market is another powerful trend that could create fortunes for astute investors. Tesla (TSLA 15.31%) is the clear leader in this important, emerging industry. Buying its stock could be your ticket to cashing in on the EV boom.

The EV industry is projected to generate over $900 billion in revenue by 2028, up from roughly $560 billion in 2023, according to Statista. As a current -- and likely future -- market share leader, Tesla stands to profit handsomely from the global shift to battery-powered vehicles. For his part, CEO Elon Musk believes Tesla could produce 20 million EVs per year by the end of the decade, up from 1.8 million in 2023.

Tesla's highly efficient manufacturing network combined with strong sales of its popular vehicles give it scale advantages over its smaller EV rivals. Its profit margins, in turn, are the envy of the auto industry. Tesla earned a whopping $10.8 billion in net income over the trailing 12 months.

This impressive profitability also enables Tesla to invest aggressively in exciting new technologies. Musk is adamant that the company's robotics initiatives will eventually eclipse its EV operations. Meanwhile, prominent investment firm Ark Invest thinks that Tesla's self-driving software could grow into an autonomous ride-hailing business that generates hundreds of billions of dollars of revenue by 2027.

This remarkable array of promising long-term growth drivers makes Tesla's stock a solid buy today.