December has been a great month for BlackBerry (TSX:BB). First, we had the acquisition agreement for the Cylance business. Then, we had the better-than-expected third-quarter fiscal 2025 results release. I know that just the mention of BlackBerry stock may bring up all kinds of mixed emotions. But read on as I review why it just may be the best stock to buy in December.

BlackBerry stock rallies big

An inflection point has finally been reached for BlackBerry. This can be seen in the company's recent results. The third quarter of fiscal 2025 exceeded the top end of the company's guidance and analyst expectations. The company returned to profitability, with positive earnings before interest, taxes, depreciation, and amortization (EBITDA) and earnings per share (EPS).

This earnings release resulted in BlackBerry rallying more than 23% in one day, on December 19. But the stock was rallying even before this. In fact, before this rally, BlackBerry stock was already up 16% in December. This was due in part to BlackBerry's agreement to sell its Cylance business, which will address Cylance's financial challenges and strengthen BlackBerry's balance sheet.

So, in all, BlackBerry's stock price has rallied 45% this month alone. But the equally exciting news is what all of this means for BlackBerry stock in the future.

The growth in the Internet of Things business

The value of BlackBerry's automotive software cannot be understated. And this is beginning to show up in the numbers — both revenue and backlog are growing fast. In the last quarter, revenue in this segment increased 13% to $62 million. This was driven by strong revenue for the digital cockpit and advanced driver assistance systems.

In the quarter, the company received more interest and more orders from various automakers. For example, BlackBerry secured an order from a German luxury automaker for QNX hypervisor for the digital cockpit. Another order came from Asia's largest automaker for different QNX systems.

Profitability at BlackBerry

After years of struggle, we are not used to seeing profitability and BlackBerry in the same sentence. But things are different now. The company has been on a mission to cut costs, extract efficiencies, and right-size the business.

This has all come together to result in a stellar performance this past quarter, with earnings before interest, taxes, depreciation, and amortization of $23 million, EPS of $0.02, and positive free cash flow. Margins have improved significantly, and BlackBerry is now in a position of being cash flow positive.

As a result of these results and new developments, analysts have been busy taking up estimates for the company. The consensus EPS estimate for 2025 was increased to break even from a loss of $0.01. In 2026, it increased by another penny to $0.08, and in 2027, it increased by $0.03 to $0.15.

The bottom line

Recent events have highlighted the value of BlackBerry. Looking ahead, the value to be realized is far greater. With the Internet of Things market continuing to grow rapidly, this puts the company on a lucrative path.

BlackBerry stock is, therefore, one of the best stocks to buy today.