A couple of stocks that have been hot buys this year are Regeneron Pharmaceuticals (REGN 0.32%) and T-Mobile US (TMUS 0.92%). These businesses defied the bear market as their strong fundamentals and continued growth gave investors reason to rally around their stocks. Unlike the S&P 500, which is down about 17% this year, these two stocks have generated positive returns of 15% or more.

But there are metrics to suggest these two stocks have more growth to come. Here's a closer look at why both of these stocks can still soar higher in 2023.

1. Regeneron Pharmaceuticals

Biotech company Regeneron focuses on creating "life-transforming medicines," and that can be good for the bottom line as well as for patients. Its business centers around its eyecare medication, Eylea (aflibercept), which today generates the bulk of Regeneron's revenue.

Eylea can help slow vision loss for people with serious eye conditions, making it a vital treatment for those who rely on it. The company is also planning to apply for a Biologics License Application for a higher dosage of aflibercept before the end of the year. It's a move that, if successful, would help drive some more bullishness behind the stock. The current treatment (2 mg) will lose patent protection in a few years, but if the higher dosage (8 mg) obtains approval from health officials, it will strengthen Regeneron's long-term growth prospects and likely result in a higher valuation for the stock.

Another crucial medicine that Regeneron can count on for continued growth next year is dermatitis medicine Dupixent, on which it shares in the profits with Sanofi. It is a vital medication as it helps children with asthma and atopic dermatitis (eczema), and is also approved for other conditions. Dupixent's sales grew at an impressive year-over-year rate of 41% through the first nine months of the year and show no signs of slowing down. By comparison, Eylea's sales have grown at a more modest 7%.

Regeneron's business is performing well, and that trend is likely to continue, given how vital its medicines are to patients. And with $4.1 billion in free cash flow over the trailing 12 months, the company looks to be in solid financial shape to handle any adversity that may come its way next year.

Year to date, the healthcare stock is up over 15% as it has been defying the bear market. But despite the increasing value, the stock isn't overpriced, trading at 17 times its future profits (based on analyst expectations), and that's in line with the S&P 500 average.

2. T-Mobile US

A stock that's been even hotter than Regeneron this year is T-Mobile US. Shares of the telecom company are up around 28% year to date as strong results have made this a highly coveted stock to own. The wireless carrier brands itself as the "un-carrier" in an effort to differentiate itself from its competitors for its focus on customer satisfaction.

The strategy has been working wonderfully for T-Mobile -- in October, it released its third-quarter results. For the third straight period, the company announced it would be raising its guidance. This year, T-Mobile is expecting between 6.2 million and 6.4 million net customer additions in its postpaid business (its previous forecast was between 6.0 million and 6.3 million). The company is also anticipating higher profitability and free cash flow and also expects greater synergies from its merger with Sprint. 

T-Mobile's focus on customer satisfaction by not raising prices and still offering fast 5G service is what could continue to lead to strong results for the business and why T-Mobile could outperform the markets next year as well. Through the first nine months of 2022, the company's sales have been flat, and profits are less than half of what they were a year ago, but the outlook is brighter now that the decommissioning of the old Sprint network is "substantially complete." 

The stock's forward P/E multiple of 20 is high when compared to rivals AT&T and Verizon Communications, which are in the single digits, but T-Mobile is still incurring merger-related expenses and is in the midst of a transition. And investors appear to be willing to pay a premium for the fast-growing business and the un-carrier's popularity with consumers.