3 Best Stocks to Buy in September

Key Points

• September's historical weakness creates compelling entry points in three diverse industries -- AI data centers, sports betting, and managed healthcare.

• Iren's 188% year-to-date surge reflects genuine AI infrastructure demand, while DraftKings capitalizes on NFL season momentum heading into the fall.

• UnitedHealth's historical decline amid DOJ investigations attracted Warren Buffett's $1.6 billion investment, signaling deep value at 18.8 times forward earnings.

• 10 stocks we like better than Iren ›

September has a dark reputation -- it's historically the weakest month for stocks. Since 1928, the S&P 500 has dropped an average of 1.2% in September, with declines in 56% of those months. Federal Reserve policy reviews, fiscal year-end budget battles, and post-summer portfolio rebalancing all fuel the narrative that this is a month to avoid.

But while everyone else reduces exposure, contrarian investors are finding extraordinary opportunities in three fundamentally different companies: an artificial intelligence (AI) infrastructure play surging 188%, a digital entertainment platform perfectly positioned for the NFL season, and Warren Buffett's newest healthcare investment trading at multiyear lows.

Where to invest $1,000 right now? Our analyst team just revealed what they believe are the 10 best stocks to buy right now. Continue »

Image source: Getty Images.

The AI gold rush meets Bitcoin's infrastructure

Iren Limited (NASDAQ: IREN) isn't your typical crypto mining story anymore. The company has pivoted hard into AI data centers, and Wall Street is just beginning to understand the implications. Up 188% year to date (as of Sept. 1, 2025) and trading at 31 times forward earnings, Iren has transformed its massive power infrastructure -- originally built for Bitcoin mining -- into something far more valuable: ready-made capacity for AI computing.

The genius lies in the infrastructure overlap. Iren already controls 2.9 gigawatts of contracted grid-connected power across renewable-heavy sites in Canada and Texas. While competitors scramble to secure power for new AI data centers -- a process that can take years -- Iren simply redirects its existing capacity. The company's results for the fourth quarter of fiscal year 2025 (ended June 30) showed revenue hitting $187 million, with full-year revenue surging 168% to $501 million. Net income swung from a $28.9 million loss to an $86.9 million profit.

The real kicker? Iren's AI cloud business is projected to generate $200 million to $250 million in annualized revenue by December 2025, with over 10,000 Nvidia GPUs online or being commissioned. The company secured $96 million in financing for Nvidia GB300 GPUs and achieved Preferred Partner status with Nvidia. As AI compute demand explodes from $45 billion today to an estimated $300 billion by 2030, companies with ready power infrastructure become kingmakers.

The business of America's new entertainment economy

DraftKings (NASDAQ: DKNG) couldn't have timed it better. The stock is up 27.2% year to date, trading at 35 times forward earnings, just as the NFL season kicks off -- the company's biggest catalyst of the year.

Q2 2025 results confirmed the momentum, with revenue surging 37% year over year to a record $1.5 billion, while net income increased to $158 million. Adjusted earnings before interest, taxes, depreciation, and amortization (EBITDA) reached $301 million, another record. User growth remained solid with 3.3 million monthly unique payers, up 6% from last year, and average revenue per payer rose 29% to $151. DraftKings reaffirmed full-year guidance of $6.2 billion to $6.4 billion in revenue and $800 million to $900 million in EBITDA, noting performance is tracking toward the upper end of both ranges.

The NFL season represents DraftKings' biggest push for user acquisition -- last year it added 1.4 million new depositors during football season alone. With 38 states already regulated, millions of customers still to capture in markets like Texas and California, and free cash flow turning positive, DraftKings has built a toll road on the digital sports economy. Seasonal tailwinds matter, but this is a structural growth story in a market still only partially unlocked.

Buffett's contrarian healthcare investment

UnitedHealth Group (NYSE: UNH) is having its worst year in memory -- down 38% since the start of 2025 while the broader market rallies. The company faces a Department of Justice criminal investigation into its Medicare billing practices and its Optum Rx pharmacy services unit. Rising medical costs have pressured margins. Leadership changes have rattled investors. It's exactly the kind of messy situation that creates extraordinary value.

Enter Warren Buffett. Berkshire Hathaway has just invested $1.6 billion to purchase 5 million shares, a massive vote of confidence from the world's greatest value investor. At 18.8 times forward earnings -- one of UnitedHealth's lowest valuations in years -- Buffett sees what panicked sellers don't: a company with unassailable competitive advantages trading at a fire-sale price.

UnitedHealth's updated 2025 guidance calls for adjusted earnings of at least $16 per share -- well below Wall Street's original $20.91 expectations -- but management expects to return to earnings growth in 2026. At today's price of roughly $310, even a modest earnings recovery should drive significant upside from these depressed levels. Buffett's move shows what this really is: not a gamble, but a chance to own the healthcare system's backbone at a discount.

Should you invest $1,000 in Iren right now?

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George Budwell has positions in Berkshire Hathaway, Bitcoin, Nvidia, and UnitedHealth Group. The Motley Fool has positions in and recommends Berkshire Hathaway, Bitcoin, and Nvidia. The Motley Fool recommends UnitedHealth Group. The Motley Fool has a disclosure policy.