Key Highlights

  • ServiceNow (NYSE:NOW) tops the list with a 26.5 percent close-to-close drop to USD 110.30 on October 29, 2026, while Intel is down about 25 percent in Friday premarket. The ranking mixes closing prices with premarket snapshots, so it is approximate.
  • Fortinet (NASDAQ:FTNT) closed 20.8 percent lower on October 29, 2026, while Reddit was indicated 20 percent to 23 percent lower in premarket. The order of third and fourth place depends on whether closes and snapshots are compared.
  • Alphabet (NASDAQ:GOOGL) finished about 12.7 percent lower at USD 283.70 on October 29, 2026, the smallest of the five. After-hours declines of 12 percent to 19 percent at Roblox, Twilio and Pinterest are excluded because those quotes are thinner.
  • Intel, Reddit (NYSE:RDDT) and ServiceNow each trace back to guidance, Alphabet to an EPS miss alongside negative free cash flow, and the Fortinet cause is contested between a quarterly beat and a lowered service Revenue forecast.

ServiceNow (NYSE:NOW): No. 1 by closing fall

ServiceNow (NYSE:NOW) fell 26.5 percent on October 29, 2026 to close at USD 110.30, the largest one-day fall among members of the S&P 500, two accounts say. The drop followed results reported on October 28, after which the shares had already fallen between 14 percent and 19 percent after hours. Adjusted EPS came in at USD 0.27. One account cites an expected USD 0.35, while another describes a miss of only USD 0.02, so the true gap is unresolved. The company guided 2026 subscription revenue to about USD 15.78 billion to 15.79 billion, and one account described Q4 guidance as weak. That explanation rests on one account and has not been checked in a filing. Subscription software is valued on forward growth. When a leader such as ServiceNow (NYSE:NOW) hints that near-term growth may slow, investors cut the multiple they pay for each dollar of future revenue, so a modest estimate cut can become a large price move. A miss at a bellwether also raises doubts about peers selling similar workflow and AI tools.

Intel (NASDAQ:INTC): Premarket gap near 25 percent

Intel (NASDAQ:INTC) published results after the close on October 29, 2026. Q3 adjusted EPS arrived at USD 0.52 against a USD 0.40 estimate, and revenue hit USD 16.5 billion, 21 percent above a year earlier. Data Center sales rose close to 80 percent to USD 7.3 billion. The weak spot is the outlook: the Q4 revenue guide of USD 15.0 billion to USD 16.0 billion and the non-GAAP EPS guide of USD 0.25 both came in short of expectations. Several summaries cite earlier estimates of about USD 17.1 billion and USD 0.43 to USD 0.44. The premarket quote of USD 68.44 sits against a prior close of about USD 92.07, a value we derived with simple arithmetic from the quoted decline. Markets price the quarters ahead, not the one just completed, so a strong quarter can still spark a sharp repricing when the outlook falls short. The reason is reported as sluggish PC demand, drawn from published market commentary rather than any company statement we could verify.

Fortinet (NASDAQ:FTNT): Second-largest S&P 500 loser

Fortinet (NASDAQ:FTNT) closed at USD 137.93 on October 29, 2026 after falling 20.8 percent, trailing only ServiceNow's 26.5 percent drop among S&P 500 members. Bank of America moved its rating to Neutral, as reported. One account says full-year service revenue was lowered, but another says headline results beat, so the cause cannot be confirmed from a filing. A third snapshot shows a further 27.5 percent drop in Friday premarket, a figure resting on one account from before the open that may not hold. Earlier, CrowdStrike and Palo Alto were already down about 6 percent after hours on October 28, which suggests the Cybersecurity sell-off began before Fortinet's own move. Security vendors earn from hardware sales, subscriptions and services. Service revenue recurs, so investors treat it as the more valuable stream, and a lower full-year service forecast signals slower growth in the part of the Business that carries the highest multiple. Fortinet (NASDAQ:FTNT) can therefore slide sharply even when headline numbers look fine, because the stock is priced on its outlook.

Reddit (NYSE:RDDT): Revenue beat, light guide

Reddit (NYSE:RDDT) posted Q3 results after the close on October 29, 2026. Revenue reached USD 895 million, up 53 percent and above estimates, EPS came in at USD 1.40, and daily active users climbed 12 percent to 130.3 million. Even so, the shares slid 16 percent to 17 percent in after-hours trading, and the premarket decline grew to 'over 20 percent' and about 23 percent on one page. That premarket range comes from a single page, so treat it as provisional. The quarter took a back seat to management's comments about the months ahead, which is where investors focused. Strong growth did not shield the stock, which shows how heavily guidance counts when expectations run high. The Q4 revenue guide of USD 1.00 billion to USD 1.03 billion falls below the USD 1.05 billion consensus, even at the top of the range. The more troubling remark came from the CEO, who warned that Q4 daily active visitors could drop by low double digits if search referral traffic keeps shrinking.

Alphabet (NASDAQ:GOOGL): Smallest of the five, largest by value

Alphabet (NASDAQ:GOOGL) reported Q3 results on October 29, 2026. EPS came in at USD 2.12, under every consensus figure we located, although those figures conflict at USD 2.94, USD 3.01 and USD 3.02. Revenue of USD 127.58 billion compared with about USD 127.9 billion expected, a slight shortfall. Google Cloud revenue reached USD 30.7 billion. Search and Advertising growth missed hopes, and free Cash Flow turned negative. The share price closed at USD 283.70, down about 12.7 percent. Because consensus EPS varies by source, the miss size is uncertain until a primary filing is reviewed. Other figures come from published market data and need filing checks. Search and advertising drive profit, so softer growth there matters more than strength in cloud. Negative free cash flow raises a second concern, since heavy data center spending absorbs cash before any revenue arrives. One summary claims roughly USD 500 billion of Market Value was erased, calling it the worst day in over 20 years. The stock's 2026 decline shows how much of the rally has unwound.

Where Things Stand

In short, the five drops share one theme, expectations reset by outlook or spending, but they do not share one cause. ServiceNow (NYSE:NOW) faces software budget worries. Intel (NASDAQ:INTC) issued a weak Q4 guide. Fortinet (NASDAQ:FTNT) has a contested cause. Reddit (NYSE:RDDT) guided below consensus and warned on traffic. Alphabet (NASDAQ:GOOGL) posted an EPS miss. The ranking blends closes with premarket snapshots, so it can shift at the 9:30 a.m. ET open on October 30, 2026. This is not Investment advice.