Key Highlights

● CarParts.com narrowed its Q2 fiscal 2026 net loss to $3.2 million from $12.7 million a year earlier, with adjusted EBITDA turning positive at $1.8 million.

● Arko Corp reported total Revenue up roughly 17% to $2.35 billion, though the company swung to a $6.1 million net loss as same-store merchandise sales eased 1.7%.

● Costco reported August 2026 net sales of $23.70 billion, up 9.9% year over year, extending a streak of double-digit growth in its most recent fiscal quarter.

● Ulta Beauty posted Q2 fiscal 2026 net sales of $3.04 billion, up 8.9%, with comparable sales up 3.8% and diluted EPS of $6.55, prompting a full-year guidance raise.

CarParts.com (NASDAQ:PRTS), Arko Corp (NASDAQ:ARKO), Costco (NASDAQ:COST), Ulta Beauty (NASDAQ:ULTA) and Walmart (NASDAQ:WMT) sample different corners of the same consumer. Within a few weeks of each other, a warehouse-club giant posted double-digit growth, a beauty specialist raised its outlook, a convenience-store operator restructured its balance sheet, an online auto-parts seller kept narrowing losses on shrinking sales, and the world's largest retailer beat expectations only to watch its shares fall.

The September 2026 Backdrop: Value Is Still Winning

The through-line across these reports is a shopper who is spending but scrutinizing. Costco's August 2026 sales rose 9.9% and Walmart's U.S. comparable sales grew 2.6% excluding fuel in its most recent quarter, both signs that scale, membership value and everyday-low-price positioning continue to pull traffic. At the same time, Arko reported a 1.7% decline in same-store merchandise sales, and CarParts.com's revenue fell more than 10%, hinting that discretionary and lower-ticket categories remain under pressure.

E-commerce is the other constant. Digital growth outpaced store growth almost everywhere it was disclosed this season, and retailers increasingly lean on higher-margin Advertising and membership income to fund price investment. That mix, resilient essentials, cautious discretionary spending, and a digital flywheel, frames every name below.

CarParts.com (NASDAQ:PRTS): Smaller, But Steadier

CarParts.com is the turnaround story of the group. For its second quarter of fiscal 2026, the online auto-parts retailer reported net revenue of $135.6 million, down 10.7% from $151.9 million a year earlier, a deliberate trade of top-line Volume for profitability and healthier unit economics.

The Margin picture improved even as sales shrank. Gross margin rose about 40 basis points to 33.2%, the net loss narrowed sharply to $3.2 million, a loss of $0.43 per share, from $12.7 million a year earlier, and adjusted EBITDA turned positive at $1.8 million, which management described as the highest since the third quarter of 2023. The company ended the quarter with $38.2 million in cash and secured a new, undrawn $25 million revolving Credit facility.

This is a Business shrinking to strength. Leadership pointed to a sixth straight quarter of operational improvement and highlighted a fulfillment Partnership approaching a $50 million annualized run rate. The open question for investors is whether PRTS can eventually re-accelerate revenue without surrendering the margin gains it has fought to build.

Arko Corp (NASDAQ:ARKO): A Balance Sheet in Motion

Arko, the convenience-store and fuel operator behind GPM Investments, delivered a quarter defined more by structure than by same-store momentum. Total revenue rose roughly 17% to $2.35 billion, but the company swung to a $6.1 million net loss attributable to Arko from a $20.1 million profit a year earlier, and adjusted EBITDA slipped 4.2% to $72.0 million.

Beneath the headline, the retail engine held up. Same-store fuel margin climbed to 48.7 cents per gallon, and merchandise margin expanded 110 basis points to 34.7%, even as same-store merchandise sales eased 1.7%. Six-month adjusted EBITDA was up 14%.

The bigger development is corporate. Following the earlier initial public offering of its wholesale-fuel subsidiary, Arko Petroleum Corp, which trades separately on the Nasdaq under APC, Arko repurchased $37.9 million of its 5.125% senior notes at a discount. Management reaffirmed full-year 2026 adjusted EBITDA guidance of $245 million to $265 million and raised its retail fuel-margin outlook.

Costco (NASDAQ:COST): The Steady Compounder

Costco remains the group's anchor of consistency. In its fiscal third quarter, reported in late May 2026, net sales rose 11.6% to $69.2 billion, alongside double-digit Earnings growth, the kind of durable expansion that has made the Warehouse club a Nasdaq mainstay.

The momentum carried into the fall. Costco reported August 2026 net sales of $23.70 billion, up 9.9% year over year, underscoring that membership renewal, treasure-hunt merchandising and grocery strength continue to compound even at enormous scale.

The near-term catalyst is timing. As of mid-September 2026, Costco had not yet released fourth-quarter fiscal 2026 results, which are expected later in the month. Investors will watch renewal rates, membership-fee income and any commentary on a potential future fee adjustment, along with E-commerce and gross-margin trends. Costco's valuation typically leaves little room for disappointment, so the risk is less about the business faltering than about a premium multiple meeting a merely good quarter.

Ulta Beauty (NASDAQ:ULTA): Raising the Bar

Ulta Beauty gave the clearest upside surprise. For its second quarter of fiscal 2026, the beauty retailer posted net sales of $3.04 billion, up 8.9%, with comparable sales rising 3.8% and Diluted Earnings per Share of $6.55, up 13.3%. Operating Margin held at 12.5%, and the store base reached 1,622 locations, including 88 international stores as Ulta extends its footprint abroad.

Crucially, management raised full-year fiscal 2026 guidance across the board: net sales growth of 6.7% to 7.2%, comparable sales growth of 3.2% to 3.7%, and diluted EPS of $28.70 to $29.00, each an increase over prior ranges.

The market's response was telling. Despite the beat and the guidance raise, shares slipped, reflecting how high expectations had climbed and lingering caution about the promotional environment in beauty. The debate now is whether Ulta's loyalty program, digital investments and international expansion can keep comps positive as it laps stronger prior-year numbers.

Walmart (NASDAQ:WMT): The Consumer Bellwether Joins the Composite

Walmart trades on the Nasdaq under the ticker WMT following its transfer from the New York Stock Exchange, making it a genuine Nasdaq Composite constituent alongside the other four names here rather than an outside comparison.

As a read on the American consumer, Walmart is indispensable. In its fiscal 2027 second quarter, ended July 31, 2026, total revenue rose about 5.9%, Walmart U.S. comparable sales grew 2.6% excluding fuel, and global e-commerce jumped 23%. Higher-margin engines shone: advertising revenue climbed 38% and membership income rose 17%, helping lift Operating Income and prompting the company to raise its full-year outlook.

Even so, the stock fell after the report, a familiar pattern in which strong results collide with elevated expectations. Walmart's numbers matter as a barometer for the group: its e-commerce acceleration validates the digital theme running through Ulta and CarParts.com, while its grocery and value strength echoes what Costco is seeing.

What Investors Should Watch

The next catalysts are concrete. Costco's fourth-quarter fiscal 2026 report, due later in September, is the closest event and the best near-term test of whether warehouse-club momentum is holding.

For Ulta, the question is durability: can comparable-sales growth stay positive against tougher comparisons, and does the international push add scale without diluting margins? For Arko, watch merchandise trends, fuel margins and the pace of deleveraging now that its wholesale arm trades separately. For CarParts.com, the pivotal signal is when revenue stabilizes so its hard-won margin gains translate into sustained profitability.

Five Retailers, Several Different Stories

Costco and Walmart show that scale, value and membership keep winning share of a cautious wallet. Ulta demonstrates that a differentiated category leader can still raise guidance. Arko is a balance-sheet-and-restructuring story more than a growth one, and CarParts.com is a disciplined turnaround trading sales for solvency. Investors should weigh each name on its own merits rather than as a single retail trade.