By Mackenzie Tatananni and Nate Wolf

August is one of the sleepiest months on Wall Street, but some stocks still swung wildly this year as summer came to a close.

A few trendy technology names brought up the rear in the S&P 500 Index amid a series of lackluster earnings reports. Many of August's winners, meanwhile, staged late-summer recoveries after brutal starts to the year.

Here are the month's top risers and fallers of as of Friday's opening bell:

Albemarle outpaced the index in August, climbing 26.8%. The company was one of several lithium producers to get a boost due to a sharp rise in the price of lithium, a key component in electric-vehicle batteries. Fears of supply snags helped: Albemarle climbed 7% on Aug. 11 after Chinese battery maker Contemporary Amperex Technology paused production at one of its mines. Shares entered August off more than 20% for the year.

Intel stock climbed 25% in what was a rollercoaster month for the U.S. chip maker. On Aug. 7, President Donald Trump called CEO Lip-Bu Tan "conflicted" and demanded he resign over alleged ties to Chinese firms. The pair quickly mended their relationship. Within weeks, the U.S. government made an $8.9 billion passive investment in Intel, becoming its single largest investor. Add that to a $2 billion investment from Japan's SoftBank and you get a banner month for the stock, which came into August down narrowly in 2025.

Idexx Laboratories rose 21.1% in August after a blockbuster earnings report on Aug. 4. The Maine-based veterinary-supply company reported better-than-expected results for its second quarter and lifted its fiscal-year earnings forecast to between $12.40 and $12.76 a share -- a 40-cent boost at the midpoint. Idexx stock has climbed 56% this year.

Human-resources software company Dayforce jumped 20.9% for the month, but it won't be trading on public markets much longer. The company reached an agreement in August to be taken private by private-equity firm Thoma Bravo in an all-cash deal worth $70 a share, delivering a 32% premium to stockholders. The deal is expected to close early next year.

If UnitedHealth Group is going to rebound from a wretched first half of the year, August was a good start. The insurer climbed 20.6% for the month, buoyed by Berkshire Hathaway buying around $1.6 billion worth of stock. The bet from Berkshire CEO Warren Buffett comes as healthcare stocks languish at their cheapest valuations in 30 years. Even after the stellar month, UnitedHealth stock remains down 40% this year.

Other stocks have been pummeled this month, such as Trade Desk, which plunged 37%. Shares crashed on Aug. 8 following the ad-tech company's second-quarter earnings report. While results were largely in line with expectations, management cautioned that revenue growth would likely slow in the third quarter. The grim outlook, coupled with the sudden departure of Chief Financial Officer Laura Schenkein announced Aug. 7, appeared to spur investor panic.

Super Micro Computer fell 28% in August. Worse-than-expected earnings for the fiscal fourth quarter might have had something to do with it. While Super Micro's revenue guidance for fiscal 2026 was encouraging, its guidance for fiscal-first-quarter revenue and adjusted earnings missed Wall Street forecasts. A selloff in stocks linked to the artificial-intelligence trade at the end of the month caused shares to slump yet again. Despite the declines, Super Micro remains up 37% this year.

Tech-oriented research firm Gartner had a challenging month, falling 27%. Commentary from CEO Gene Hall on Aug. 5 caused shares to close at their lowest level in three years and see the largest same-day percent decrease since 1999. Hall remarked that confidence among chief executives in the U.S. had dropped to recessionary levels in the second quarter. The company also cut its full-year revenue forecast, which overshadowed an otherwise solid earnings report.

Fortinet stock declined 21% in August. Shares sank on Aug. 7 after the cybersecurity company posted numbers that edged by estimates, but issued a weak outlook for firewall-product upgrades. Analysts remarked at the time that they saw "a challenging setup going forward," as the industry refresh cycle for firewall services appears to have peaked earlier this year.

Rounding out the list of the biggest losers was Coinbase Global, which fell 19%. The cryptocurrency exchange reported below-consensus earnings after the closing bell on July 31, causing the stock to tumble and extend its losses into the next day. Shares fell on Aug. 5 after the company unveiled a convertible note offering worth up to $2.3 billion, raising concerns about potential dilution. Then, Coinbase declined yet again in mid-August amid a broader selloff in fintech stocks.

Write to Mackenzie Tatananni at mackenzie.tatananni@barrons.com and Nate Wolf at nate.wolf@barrons.com

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August 29, 2025 14:36 ET (18:36 GMT)

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