Key Highlights

  • Seagate (NASDAQ:STX) fell about 6% to 7% after hours despite adjusted EPS of USD 7.68 against USD 7.39 and a next-quarter revenue guide of USD 4.70 billion to USD 4.90 billion, with profit-taking one unconfirmed explanation.
  • Enphase (NASDAQ:ENPH) plunged 10% to 15.7% after hours on a fourth-quarter revenue guide of USD 225 million to USD 255 million against about USD 300 million expected, citing weak United States residential demand and European destocking.
  • CoStar (NASDAQ:CSGP) dropped about 10% to 11% despite EPS of USD 0.38 against USD 0.34 and revenue of USD 952 million, as spending on its residential marketplace weighed on margins.
  • NXP Semiconductors (NASDAQ:NXPI) fell about 7.4% with no cause retrieved, while Teradyne fell about 6.6% despite a beat and a 59.5% year-to-date gain, so neither move has a company-stated cause.

Seagate (NASDAQ:STX): Beat and raise, still sold

After the close on October 27, 2026, Seagate (NASDAQ:STX) reported adjusted EPS of USD 7.68 against USD 7.39 expected, revenue of USD 4.20 billion, and a revenue guide for the next quarter of USD 4.70 billion to USD 4.90 billion. Those figures beat estimates and the guide was raised, yet the shares fell in after-hours trading. Quotes ranged from a 6.04% decline to about 7%. The explanation offered in one market account is profit-taking after a strong run for an AI storage name. That reason is not confirmed by the company release, so it should be read as commentary. The shares trade in a thin after-hours market, where one large order can move the price by several points. Hard drive makers are priced as beneficiaries of AI data growth, because models and the data they use need large amounts of storage. When a stock has risen strongly, investors tend to expect more than a modest beat, a so-called whisper number above published consensus. The EPS beat was USD 0.29, about 3.9%, simple arithmetic. The guide midpoint of USD 4.80 billion is roughly 14% above the quarter's USD 4.20 billion, which is strong growth, yet the market may have wanted a larger step.

Enphase (NASDAQ:ENPH): Weak revenue guide

After the close on October 27, 2026, Enphase (NASDAQ:ENPH) reported third-quarter EPS of USD 0.41 against USD 0.51 expected and revenue of USD 293 million against USD 304 million expected. The larger shock was the outlook: fourth-quarter revenue was guided to USD 225 million to USD 255 million, against about USD 300 million forecast by analysts. Shares fell sharply after hours, with quotes ranging from about 10% to 15.73% depending on the quote used, which makes the true size of the drop uncertain. The company attributed the weakness to softer residential demand in the United States and destocking in Europe, according to the company release. Enphase sells microinverters and related products to installers and distributors who put them on homes. When residential solar demand slows, installers order less. Destocking occurs when distributors sell down their existing inventory instead of buying new products, which cuts the maker's revenue even if end demand is stable.

CoStar (NASDAQ:CSGP): Margin pressure from spending

After the close on October 27, 2026, CoStar (NASDAQ:CSGP) reported EPS of USD 0.38 against USD 0.34 expected and revenue of USD 952 million. Even with the beat, the shares fell about 10% to 11% in after-hours trading, with one quote at 10.09% and another at 11%. The company release, as reported, points to heavy spending on its residential property marketplace, which weighed on margins. The figures behind the margin decline, the guidance and the spending plan were not retrieved for this article, so they are not stated. The company filing contains the full income statement. The reaction shows that the market now cares more about margin discipline than about a modest earnings beat in this stock. The tension in this report is a familiar one: a company chooses to spend heavily to build a new business, and investors must decide whether the spending will pay off. CoStar is best known for commercial real estate data and listings, and its residential marketplace competes with established portals that already have large audiences. Marketing and product spending are costs today, while revenue from the new line may take years to build.

NXP Semiconductors (NASDAQ:NXPI): No cause retrieved

After the close on October 27, 2026, NXP Semiconductors (NASDAQ:NXPI) traded down about 7.4% according to published market data. The results, guidance and any company comments behind the move were not retrieved for this article, so no reason is stated and none should be assumed. The move followed a strong regular session for chip stocks, when the Philadelphia Semiconductor Index rose 3.60% and the Kospi jumped 6.63% overnight on record profit at SK Hynix. A fall of this size after hours is notable, but it is one data point from thin trading, and it may change when regular trading opens on October 28. The decline also arrived on the same evening as results from several large companies, which can crowd the news flow and add to volatility. NXP makes semiconductors for cars, industrial equipment and connected devices, so its results are read as a gauge of demand in those end markets rather than of artificial intelligence spending. After a broad chip rally, investors often look for companies whose guidance does not match the optimism in the price. An after-hours decline can reflect results, guidance or simple profit-taking, and which of these applies here is not known.

Teradyne (NASDAQ:TER): Sold after a 59.5% run

After the close on October 27, 2026, Teradyne (NASDAQ:TER) fell about 6.6% in after-hours trading even though it beat estimates, according to published market data. The estimate, the reported figures and the guidance were not retrieved for this article, so the size of the beat is not stated. The shares had risen 59.5% since the start of 2026, which means investors expected a strong report and were ready to take gains. One market account describes the decline as profit-taking in chip testing, but that explanation is not confirmed by the company and should be treated as interpretation. The numbers behind the beat should be read in the company filing, which sets out orders and margins in more detail than the market summary. Teradyne makes automated test equipment that checks semiconductors and electronic systems before they ship, so demand follows chip production and new device launches. Orders can rise quickly when chipmakers expand capacity, which is why the stock gained so much in 2026, and they can fall quickly when customers pause spending. A strong run raises the question of how much good news is already in the price.

Where Things Stand

The answer is that these five fell after hours for different reasons. Seagate (NASDAQ:STX) was sold after a beat and raise. Enphase (NASDAQ:ENPH) gave a weak guide. CoStar (NASDAQ:CSGP) faced margin worries. NXP Semiconductors (NASDAQ:NXPI) has no stated cause. Teradyne (NASDAQ:TER) fell after a 59.5% gain. After-hours moves are approximate and thinly traded. Regular trading on October 28 and the Federal Reserve decision are the next tests. This is not investment advice.