The biggest drops of the past seven days span leadership chaos, earnings misses, analyst downgrades and a market-wide risk retreat driven by the Federal Reserve's hawkish tone. Here are the standout declines.
MongoDB (MDB) — Down ~15–24% | Sept. 28
The sharpest headline loss of the week came when database software company MongoDB disclosed that CEO Chirantan "CJ" Desai had resigned effective immediately to lead a new AI initiative at Meta Platforms — one day before MongoDB's own Investor Day. Shares cratered roughly 15–24% depending on the session snapshot, with premarket trading showing the steepest drop.
Dev Ittycheria, who led the company from 2014 to 2025, returned as interim CEO, and an executive search firm has been retained. MongoDB reaffirmed its full-year fiscal 2027 guidance, but the abrupt leadership exit — Desai had been in post less than a year — spooked investors. The stock sat at around $323 as of late September, some 31.5% below its August 52-week high of $472.29.
Skydance (SKYD) — Down 7.71% | Oct. 7
Shares in Skydance, formed by the 2025 merger of Skydance Media and Paramount Global, fell 7.71% on their second day of public trading. No specific negative catalyst was cited; the decline appears to reflect post-listing volatility and profit-taking in a softer tape.
Allegion (ALLE) — Down 6% | Oct. 7
The security products manufacturer slid 6% on Wednesday as risk-off sentiment hit industrial stocks broadly, tied to rising Treasury yields (10-year above 5.3%) and renewed oil market fears.
Comfort Systems USA (FIX) — Down 5.91% | Oct. 7
Mechanical and electrical contractor Comfort Systems fell 5.91% after Zacks Research downgraded the stock from Strong Buy to Hold, removing one of the more prominent buy ratings on the name.
Constellation Brands (STZ) — Down ~4.76% | Oct. 7
The beer and spirits company fell nearly 5% in premarket after reporting quarterly results that missed Wall Street consensus estimates, despite beating headline revenue and EPS figures. The company reaffirmed its full-year profit outlook, but the miss on expectations was enough to trigger selling. Analysts at BofA had already cut STZ to Underperform earlier in the year, citing weaker beer volumes and margin pressure.
What This Means
Three of these five declines are company-specific — a CEO shock, a downgrade, an earnings miss — while two (Allegion, Skydance) reflect the broader macro mood as Fed rate-hike fears push investors toward caution. For portfolio managers: leadership-change risk is a live theme heading into Q4, MongoDB being the clearest example. For traders watching industrials, the rate-sensitivity of names like Allegion and Comfort Systems makes the October 28 Fed decision a direct catalyst to watch.
Sources
- Why MongoDB (MDB) Stock Is Nosediving – Wedbush/StockStory (Sept. 28, 2026)
- Meta Poaches MongoDB CEO "Effective Immediately" — Stock Sinks 24% – TIKR
- Stock Market Today Oct. 7, 2026 – TheStreet
- Why Constellation Brands (STZ) Shares Are Plunging – Finviz
- Top Stock Losers This Week – Stock Analysis