Netflix, MercadoLibre, and Tesla Are All Underperforming the S&P 500. Here's the 1 Stock I'd Buy in September.

Netflix (NASDAQ: NFLX), MercadoLibre (NASDAQ: MELI), and Tesla (NASDAQ: TSLA) are having a challenging year. The three stocks are trading 14%, 3%, and 21% lower, respectively, in 2026. They are all trailing the otherwise rising general market.

The good news is that all three companies are still growing, even as their share prices are shrinking. They are very different businesses with strong brands and sticky customer loyalty. All three may be market laggards lately, but let's take a closer look at all of them before I tell you the one that I would buy in September.

Image source: Getty Images.

1. Netflix

Have you streamed through all five seasons of Stranger Things? Investors have been experiencing "The Upside Down" in just the last three quarters. The same company that posted its strongest revenue growth in four years in the fourth quarter of last year now finds itself bracing for its weakest top-line growth in the current quarter.

Netflix stock has responded to the deceleration, losing more than a third of its value since peaking last summer. The global platform continues to grow, now with roughly 325 million subscribers worldwide. I say "roughly" because Netflix stopped offering up quarterly subscriber numbers after topping 300 million at the end of 2024.

The valuation looks compelling, not a surprise when a stock slides for a growing -- albeit, slowing -- business. Revenue growth has decelerated from 18% to the 11.7% Netflix is targeting for the quarter ending later this month. It's still double-digit growth, but that's not even the best part.

The bottom line at Netflix has grown about twice as fast as revenue over the last three quarters. The stock that has historically commanded a chunky premium to the market is now trading at a reasonable 25 times trailing earnings and a compelling 21 times next year's profit target.

2. MercadoLibre

The resiliency of the Latin American e-commerce and fintech markets is worth celebrating. Despite political instability, pockets of hyperinflation, and class warfare challenges, folks continue to spend money. MercadoLibre is the obvious beneficiary.

The pioneer in e-commerce and online payments has become a juggernaut. Top-line growth has been consistently robust. Net revenue has topped 30% for 30 consecutive quarters, with the 50% jump it posted this summer clocking in as its strongest top-line jump in four years.

The bottom line is another story. Initial loan-loss provisions as it expands into the region's credit markets with loans and credit card offerings are weighing on near-term profits. Zooming in on its largest market, Brazil, MercadoLibre has had to subsidize free shipping for smaller orders to stay ahead of cost-cutting international competitors.

This all comes together for a quarterly cadence of steady top-line beats and many bottom-line whiffs, but that's a sacrifice investors should be willing to make. With the Latin American market still early in the e-commerce and fintech migration compared to the U.S., Europe, and most Asian markets, grabbing market share is more important than boosting its immediate profitability.

3. Tesla

This brings us to Tesla stock. It's the world's most valuable automaker by market cap, but it's naturally more than just a maker of popular electric vehicles. It has the largest network of proprietary charging stations. It's a leader in autonomous driving, and its next market to conquer will be home robotics.

Despite posting its strongest revenue growth in three years in its latest quarter, the impressive 26% year-over-year jump was offset by the way Tesla got there. Heavy promotional activity in Europe to clear out excess inventory while also capitalizing on the surge in gas prices was good for sales but rough on margins. Investments in humanoid robotics and other emerging tech also took a larger bite than expected. Free cash flow turned negative, and profitability was cut in half.

Improving its FSD (full self-driving) platform, rolling out its fleet of robotaxis, and making a big push into home robots should pay off in time. For now, investors are moving to the sidelines until there is more visibility to justify its sizable valuation.

A September to remember

There's a strong bullish argument to be made for all three companies, and I personally own two of them. Tesla is the one I don't own right now. I'm not likely to be a buyer in September. Despite suffering the largest decline of the three through the first eight months of 2026, the valuation remains rich until it can prove it can corner the market in consumer robotics.

Netflix offers the most compelling earnings-based valuation, but it's also growing the slowest. Analysts see revenue rising a modest 45% through the next four years, compared to doubling for Tesla and rising 145% for MercadoLibre. The recent trend of decelerating revenue growth could get in the way of its near-term momentum.

This leaves MercadoLibre as the stock I am most likely to buy in September, adding to my existing position. It's making near-term margin sacrifices like Tesla, but the payoff should come sooner with less uncertainty. Trading at a historically reasonable 35 times next year's profit target, given its heady historical growth rate, makes it the stock to buy this month.

Rick Munarriz has positions in MercadoLibre and Netflix. The Motley Fool has positions in and recommends MercadoLibre, Netflix, and Tesla. The Motley Fool has a disclosure policy.