Fact check: The S&P 500 just had its best day of 2026…

Verdict: mostly true — Trust Score 85/100

The Instagram post accurately reports major market movements and geopolitical events for March 31, 2026, including the S&P 500's significant gain, Iran's President's statement on ending the war, and the national gas price crossing $4/gallon. There are minor inconsistencies in some reported percentage gains for market indices and unverified specific market cap figures.

Platform
instagram
Source author
quantdata — see all fact-checks of this account
Original post
https://www.instagram.com/p/DWkF1cBiTXD/?igsh=MTc4MmM1YmI2Ng==
Verified on
April 1, 2026
Verification ID
QAfwrCM7qvs

Original content reviewed

Platform: INSTAGRAM Author: @quantdata --- Caption/Description --- The S&P 500 just had its best day of 2026… The index gained ~$1.7 trillion in market, jumping 2.9% and having its best day since May 2025. 📈 This came after Irans President said they are willing to end the war pending security guarantees from the United States. 👀 NVIDIA, which makes up 8% of the S&P 500 gained over $200 billion in market cap today. For perspective, that’s bigger than Disney… The Volatility Index just recorded its 2nd largest drop of 2026, falling 17%. Even with today’s drop, the $VIX is still up 68.9% YTD. 🤯 What will the first day of the new quarter bring tomorrow, hopefully not a April fools joke 🥲 --- Carousel/Slides (10 items) --- Slide 1 (image): Text: MARKET NEWS THE S&P 500 GAINED $1.7 TRILLION IN MARKET CAP, THE BEST DAY OF 2026 Quant Data NVDA +5.66% MSFT +3.20% TSLA +6.43% WMT +0.64% AAPL +2.94% AMZN +3.72% TSM +6.82% VOO +3.05% GOOGL +5.19% GOOG +5.04% Slide 2 (image): Text: It's so over It's over We're back We're so back We are here Slide 3 (image): Text: BREAKING: Iran’s President Pezeshkian says Iran is prepared to end the war with the U.S., pending guarantees. Market Update: 🔵 Nasdaq +2.64% 🔵 S&P 500 +2.23% 🔵 Dow Jones +1.56% Slide 4 (image): Text: Nvidia gained over $200 billion in market cap today, jumping 5.62% 📈 Don’t forget, Nvidia makes up 8% of the entire S&P 500 index 😳 TECH CONFERENCE Slide 5 (image): Text: March 31st...the best trading day of 2026 Slide 6 (image): Text: the $VIX is sliding sharply today, with markets pricing in a clear de-escalation in Iran war risk. the volatility index on track for its 3rd largest pullback of 2026. Volatility S&P 500 Index • 1D • TVC VIX 1D Volatility S&P 500 Index Slide 7 (image): Text: this is insane... the market is now pricing in no rate cuts until September 2027...yes September 2027, where a 25–50bps cut is actually seen as more likely th

Claims analyzed (15)

  1. verified: The S&P 500 just had its best day of 2026…
    Multiple news sources confirm that the S&P 500 surged 2.9% on March 31, 2026, marking its largest gain since May (last spring), which would qualify it as its best day of 2026 so far.
  2. mostly true: The index gained ~$1.7 trillion in market, jumping 2.9% and having its best day since May 2025.
    The S&P 500 did jump 2.9% (or 2.91%) on March 31, 2026, and it was its largest gain since May (last spring). While the exact '$1.7 trillion in market' gain is not explicitly stated in the search results, a 2.9% increase for an index of the S&P 500's size would represent a substantial dollar value.
  3. verified: This came after Irans President said they are willing to end the war pending security guarantees from the United States.
    Iranian President Masoud Pezeshkian (who has been president since 2024) stated on March 31, 2026, that Iran has the 'will to end this war' on the condition that 'essential prerequisites' are met, specifically security guarantees to prevent future aggression. This statement was made during a phone call with European Council President António Costa.
  4. verified: BREAKING: Iran's President Pezeshkian says Iran is prepared to end the war with the U.S., pending guarantees.
    On March 31, 2026, Iranian President Masoud Pezeshkian stated that Iran has the 'will to end this war' on the condition that 'essential prerequisites' are met, especially security guarantees to prevent repetition of aggression. This was reported by multiple news outlets.
  5. mostly true: NVIDIA, which makes up 8% of the S&P 500 gained over $200 billion in market cap today. For perspective, that’s bigger than Disney…
    NVIDIA (NVDA) did rise 5.6% (or 5.56%) on March 31, 2026, and was a significant contributor to the S&P 500's gains. While the exact '$200 billion in market cap' gain, the '8% of S&P 500' weighting, and the 'bigger than Disney' comparison are not explicitly confirmed by the search results, a 5.6% gain for a company of NVIDIA's size would equate to a substantial market cap increase.
  6. mostly true: Nvidia gained over $200 billion in market cap today, jumping 5.62%
    NVIDIA (NVDA) rose 5.6% (or 5.56%) on March 31, 2026. The specific '$200 billion in market cap' gain is not explicitly confirmed by the search results, but a 5.6% jump for a company of NVIDIA's valuation would be a substantial amount.
  7. unverifiable: Nvidia makes up 8% of the entire S&P 500 index
    The search results did not confirm NVIDIA's specific weighting (8%) within the S&P 500 index for March 31, 2026.
  8. mixed: The Volatility Index just recorded its 2nd largest drop of 2026, falling 17%. Even with today’s drop, the $VIX is still up 68.9% YTD.
    The VIX did fall significantly on March 31, 2026, with one source reporting a -17.51% drop. However, the claim of it being the '2nd largest drop of 2026' and 'still up 68.9% YTD' could not be explicitly confirmed or refuted by the provided search results.
  9. unverifiable: The Volatility Index just recorded its 2nd largest drop of 2026
    While the VIX had a significant drop on March 31, 2026, the search results do not confirm its specific ranking as the '2nd largest drop of 2026'.
  10. mostly true: the $VIX is sliding sharply today, with markets pricing in a clear de-escalation in Iran war risk. the volatility index on track for its 3rd largest pullback of 2026.
    The VIX did slide sharply on March 31, 2026, with a reported drop of 17.51%. This was linked to hopes of de-escalation in the Iran war. However, the claim of it being the '3rd largest pullback of 2026' could not be explicitly confirmed by the search results, and it contradicts the caption's '2nd largest drop'.
  11. verified: March 31st…the best trading day of 2026
    Multiple sources confirm that March 31, 2026, was a strong trading day, with the S&P 500 having its largest gain since May (last spring), indicating it was indeed the best trading day of 2026 so far.
  12. false: Market Update: Nasdaq +2.64%, S&P 500 +2.23%, Dow Jones +1.56%
    These figures are inconsistent with multiple news reports for March 31, 2026. Actual reported gains were: Nasdaq +3.8% (or +3.83%), S&P 500 +2.9% (or +2.91%), and Dow Jones +2.5% (or +2.49%).
  13. unverifiable: the market is now pricing in no rate cuts until September 2027…yes September 2027, where a 25–50bps cut is actually seen as more likely than a continued hold.
    The search results did not provide specific CME FedWatch Tool data or market sentiment analysis for March 31, 2026, regarding rate cut probabilities for September 2027.
  14. verified: The national gas price average has just crossed $4/gallon for the first time since August 7th, 2022. Prices are now up over $1.05/gallon in just 1 month.
    On March 31, 2026, the national average price for a gallon of regular gas climbed to $4.018 (or $4.02), crossing the $4 threshold for the first time since 2022 (or more than three years). Prices were up over $1 per gallon compared to a month prior, before the Iran war began, with AAA data showing the national average at $2.98 a gallon on February 27, 2026.
  15. unverifiable: Gold just logged its steepest monthly decline in over 12 years, falling more than 10% in March alone.
    The search results did not provide specific information confirming gold's performance for March 2026, particularly a 'steepest monthly decline in over 12 years, falling more than 10%'. One source mentions 'precious metals' being weighed down but without specific figures for gold.

Related verifications

AI-generated analysis. Not a substitute for professional fact-checking.