There are over 1,500 companies listed on the UK stock market today. Clearly, that’s enough to contain many potential hidden gems, including obscure small-caps.

However, I want to spotlight two established companies here. While they’re both in the FTSE 250, they probably still fly under the radar of most investors today.

Growing global business

The first stock is Applied Nutrition (LSE:APN). This sports nutrition company only listed in late 2024 and currently has a £544m market-cap.

However, the firm is quickly making a name for itself, with shelf space secured for its products in Tesco, Asda, Morrisons, Sainsbury’s, and Holland & Barrett. Its Vimto-flavoured hydration tablets and isotonic gels are very popular.

Around 90% of revenue comes from business-to-business channels, including large retailers, gym groups, and international distributors it sells in bulk to. Indeed, over half of sales now come from overseas.

Globally, the sports nutrition and wellness market is booming, with younger generations seeing health and fitness as a core part of their lifestyle. As such, vitamins and supplements are increasingly part of their daily routine, as normal as brushing their teeth.

Therefore, I consider this sector to be moving more towards consumer staples. And many people are willing to pay a little more for quality, which is creating a big opportunity for Applied Nutrition’s trusted products.

For the current fiscal year ending July, the company’s revenue is expected to jump 31% to £140m. City analysts reckon it could reach almost £200m by 2029, with healthy profitability alongside.

Arguably the biggest threat to near-term growth is the Middle East conflict, which is still causing shipping disruption. Rising inflation (particularly for whey protein) could also pressurise margins.

On the other hand, I think the valuation’s reasonable, with a forward price-to-earnings (P/E) ratio of 17.8.

A final thing I like is that the company’s founder-led by CEO Thomas Ryder, who’s very ambitious to grow the brand’s trustworthiness globally.

Green economy shift

With its £1.3bn market-cap, Volution (LSE:FAN) is a larger FTSE 250 company. Its share price is up around 350% since listing in 2014.

The company designs and manufactures indoor air quality solutions. Revenue has more than doubled over the past five years, driven by the ventilation specialist’s acquisition-led growth strategy.

In the six months to 31 January, revenue rose 21.7% to £228.7m, with a solid 22.6% operating margin. And 72.1% of sales came from low-carbon products (like heat recovery systems), up from 68% the year before.

Now, the risk to growth is the struggling UK construction market, which is being held back by high interest rates and inflation. Any deterioration here, which can’t be ruled out, could present challenges.

Given this risk, I’m encouraged to see the firm diversifying its revenue base further with the acquisition of AC Industries in Australia. This move gives Volution exposure to the gold and copper mining ventilation sector.  

The stock also pays a dividend. While the forward yield of 1.9% isn’t much to write home about, the annual payout’s been growing between 9% and 20% in recent years.

Volution has strong long-term growth potential, with building regulations mandating better energy-efficient ventilation. Pair this with a reasonable forward P/E ratio of 17, and I think the stock’s worth considering as a green energy play.