As giant companies, especially in technology, propel the S&P 500 to new heights, a select group of mid-sized companies in niches from patent licensing and solar energy equipment to apparel are outperforming.
Inthe competition among the world’s top smartphone makers—Apple, Samsung, Google and China’s Xiaomi—to incorporate AI advancements into their products, it can be hard for investors to forecast winners and losers. But one thing is certain. They all depend in part on a little-known research and development firm in Wilmington, Deleware called InterDigital.
So far this year, InterDigital’s stock has surged 87%, propelled by its portfolio of 38,000 patents covering advancements in cellular wireless technology, video streaming and AI processing. The majority of its 430 employees are engineers and scientists, many of them phDs, working in essentially for-profit academic research labs. Its $929 million in 12-month sales, up 29% year over year, comes from the royalties it gets licensing those patents to big-name consumer tech retailers and media businesses.
“Combining AI technology, video and wireless together, we are one of the very few companies in the world who has expertise in all three of them,” says CEO Liren Chen, himself a holder of over 100 patents, who took over the business in 2021 after serving as Qualcomm’s head of intellectual property. “Video consumption is going through the roof, and most video is consumed on the wireless network.”
InterDigital hires PhD students and researchers to labs from Los Altos, California, to Rennes, France, and adds on average six new patents every day. It has particularly grown in video in the last five years, now claiming 10,000 patents in the sector. Its methods of coding and compressing video efficiently using as little bandwidth as possible helps viewers stream shows and movies without buffering, and it also has patents that make colors more vibrant and use AI technology to reduce power consumption while watching video.
InterDigital doesn’t license exclusively to any customer, instead creating open industry standards and ensuring its technology is part of those standards. Its business model comes with a legal cost to protect its intellectual property—those expenses were $56 million in 2024—but it has still managed to record $498 million in net profit in the last year, with operating margins climbing above 60%.
Those results help InterDigital rank first on Forbes’ 2025 list of America’s Most Successful Mid-Cap Companies, which analyzed stocks with market caps between $5 billion and $20 billion. The rankings are based on stock performance, sales growth, return on equity and earnings growth for the last five years, with more weight given to the last 12 months of data. Companies which had share prices below $5 or whose revenues declined in the last 12 months did not qualify for the list.
Both small and mid-cap stocks have lagged behind large caps for years, and the trend has persisted this year. The S&P MidCap 400 is up only 5.7% year-to-date, trailing the S&P 500’s 16.3% gain, though the large-cap index has been increasingly concentrated in technology stocks and expensive. The S&P 500’s 10 largest constituents make up 40% of the index, which trades at 30 times earnings. The S&P 400 is more evenly distributed among its components with market caps ranging from $870 million to $34 billion, and trades at a more typical 20 times earnings.
Nextpower’s trackers tilt solar panels to optimize the amount of sunlight they get and can angle them to avoid hailstorms and other weather events.
Courtesy of Nextpower
One stock that has outperformed most of the others in the index is Nextpower, which generates most of its $3.4 billion in annual sales from selling solar trackers, which use automated technology to tilt and rotate solar panels in the direction of the sun. Despite President Trump’s public disdain for renewables, calling wind and solar energy the “scam of the century” in one Truth Social post in August, solar is still growing. Solar energy generated 474 more Terawatt-hours of power in 2024 worldwide compared with 2023, more than twice as large a increase as any other form of electricity. Goldman Sachs researchers expect solar installations to rise another 57% by 2030 as costs continue to decrease.
“Starting about five to seven years ago, solar crossed over as the lowest cost way to generate power, absent subsidies, in most places on earth,” says Dan Shugar, Nextpower’s founder and CEO. “We’re in an electricity super cycle right now, and it’s the early days of that. Demand is growing like crazy.”
Based in Fremont, California, Nextpower is No. 5 on Forbes’ mid-cap list, with its stock up 140% in the past year. Its $576 million in net income in the last 12 months has grown more than fivefold in two years, and in November, the company renamed itself from Nextracker to Nextpower to reflect its broadening ambitions. It’s the world’s leading provider of solar trackers, which account for 87% of its revenue, but that percentage will drop after buying several businesses in the last two years that build foundations for solar farms and use robots to do on-site inspections, among other offerings.
Elsewhere on the list are more recognizable names to consumers like retailers Boot Barn (No. 13), Urban Outfitters (No. 26), Deckers (No. 77) and Levi’s (No. 94). Boot Barn shares fell nearly 50% between January and April this year on tariff fears, since Mexico is a manufacturing hub for its leather cowboy boots, but as those policies were softened, its shares more than recouped those losses with a 120% rally since then. It has doubled its footprint from 250 stores at the end of 2019 to 500 today, a much faster rate of growth than almost all of its peers, and its 12-month sales are up 18% to $2.1 billion. It has also improved its merchandising in that span to offer a larger selection of other apparel like flannel shirts and trucker hats, according to William Blair analyst Dylan Carden.
Boot Barn has locations in 49 states now, anchored by dozens of stores in both Texas and California.
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“Your typical Boot Barn customer blows out their boots on the work site once a year, they’ll go into a store because they need a pair for the next day, and maybe they’ll pick up something else,” Carden says. “It’s a relatively evergreen purchase.”
In between InterDigital and Nextpower, the rest of the companies making up the top five are Halozyme Therapeutics, a biotech firm developing cancer treatments; electrical infrastructure provider IES Holdings, which has flourished on the need to power data centers for AI projects; and Brinker International, the parent company of restaurant chains Chili’s and Maggiano’s.
Brinker is one of several stocks on the list that has flatlined this year despite strong fundamentals. It owes its fourth-place ranking to a high return on equity and 23% year-over-year sales growth, but its stock is down 1% this year after soaring 230% in 2024. Another casual chain Texas Roadhouse has posted double-digit sales growth and is ranked No. 50, though its shares are down 8% this year. Declining consumer sentiment and inflation may be scaring investors away from companies that rely on Americans dining out, but for bubble-conscious investors looking for areas of the market that haven’t ballooned in the AI craze, restaurant stocks still recording steady growth could be an appetizing option.