AI-Related Lawsuits Drive Sharp Rise In Securities Class Action Filings

Securities class action filings jumped to 121 in H1 2026 from 93 in the previous six months, with AI-related cases and mega-dollar-loss litigation fueling the surge, according to Cornerstone Research and Stanford Law School.
By: | August 18, 2026
Stock chart illustrating securities litigation

Securities class action filings increased in the first half of 2026, climbing to 121 from 93 in the second half of 2025, and 114 in the first half of 2025, according to the 2026 Midyear Assessment of Securities Class Action Filings by Cornerstone Research and the Stanford Law School Securities Class Action Clearinghouse.

Core filings, which exclude merger and acquisition litigation, reached 117 in H1 2026, up from 90 in H2 2025 and well above the 1997-2025 historical semiannual average of 97.

The Disclosure Dollar Loss (DDL) Index — which the report uses to measure market capitalization changes between the last trading day before and after a class period ends — reached $529 billion in H1 from $299 billion in the second half of 2025, nearly matching the all-time high of $544 billion set in 2022’s first half, the report said.

The Maximum Dollar Loss (MDL) Index, tracking market cap declines between a company’s peak price during the class period and the day following its end, rose to $1,858 billion in H1 from $1,000 billion in H2 2025, substantially above the 1997-2025 semiannual average of $667 billion, Cornerstone Research found.

AI Litigation Accelerates

Filings tied to artificial intelligence were the standout trend in the first half of 2026, with 15 such cases, on pace to nearly double the full-year 2025 total of 16 when annualized to 30, according to the report. Of the 15 AI-related filings, seven concerned AI development, five involved data centers, and four involved AI infrastructure or hardware. Notably, there were no AI-related filings concerning autonomous vehicles in the first half of 2026, a departure from prior years, the report said.

Although AI-related filings made up just 13% of total core filings, they accounted for a disproportionate share of market capitalization losses. The DDL from these filings, $385 billion, represented 73% of the total DDL Index in H1, while the MDL from AI-related filings, $1,349 billion, also made up 73% of the MDL Index, according to Cornerstone Research.

Two of the 15 AI-related filings alone accounted for $1,235 billion, or 66%, of the MDL Index. AI-related filings were concentrated in the 9th U.S. Circuit Court of Appels (six filings), followed by the 2nd and 3rd Circuits (three each), the report said.

Other litigation trends moved in the opposite direction. The annualized number of cryptocurrency-related filings, six, is on pace to be the lowest since 2019, and there were no COVID-19 or cybersecurity-related filings in the first half of 2026, the first such absence since 2019 and 2016, respectively, according to the report.

Mega Filings And Rising Stock Price Drops

Mega filings, those with a DDL of at least $5 billion or an MDL of at least $10 billion, accounted for an outsized share of market capitalization losses in the first half, according to Cornerstone Research. Mega filings represented 85% of total DDL, the third-highest percentage on record behind 2022’s H1 (89%) and 2000’s H1 (88%), the report found.

Mega filings also made up 90% of total MDL in the first half, above the 1997-2025 semiannual average of 81%. AI-related filings comprised at least 80% of both Mega DDL and Mega MDL in the period, according to the report.

Technology Sector And Emerging Allegations

The number of filings in the Technology sector reached 24 in the first half, up from nine in the second half of 2025, twice the 1997-2025 semiannual average, driven largely by the AI filing surge, the report said. Technology filings accounted for $1,445 billion in MDL, the largest of any sector, followed by Consumer Non-Cyclical ($235 billion) and Financial ($65 billion). In the Consumer Non-Cyclical sector, 29 of 44 filings, or 66%, involved biotechnology, pharmaceuticals, and health care-related subsectors, according to Cornerstone Research.

The 2d and 9th Circuits together accounted for 70% of core federal filings in the first half of 2026 (80 of 115), up from 64% in H2 2025 (57 of 89), the report said.

Cornerstone Research also identified emerging allegation patterns beginning in late 2025: 10 filings alleging “pump-and-dump” schemes, six with tariff-related allegations, and four involving private credit and business development companies. Nine of the 10 pump-and-dump filings were brought against non-U.S. issuers, and those filings carried a median stock price drop of 85%, far above the 23% median for all H1 filings, according to the report.

Obtain the full report here.

The R&I Editorial Team can be reached at [email protected].

More from Risk & Insurance