Mitsui Chemicals shares plunge 13.6% on $11.6bn JSR acquisition

The chemical maker announced a deal for JSR exceeding its own market capitalisation, triggering a sharp sell-off.

The chemical maker announced a deal for JSR exceeding its own market capitalisation, triggering a sharp sell-off. Published 2026-11-09 by Falling Shares.

2026-11-09 | By Falling Shares Intelligence, edited by Wung Thomas, Editor-in-Chief

Written by Falling Shares Intelligence, our automated newsroom, from the public sources listed below and live market data. Every figure is checked against that material before publication, but the story has not been reviewed by a human editor. Check the linked sources before relying on it, and report errors to info@fallingshares.com.

Shares in Mitsui Chemicals fell 13.62% on Monday after the company announced plans to acquire chipmaking materials maker JSR for $11.6 billion. The transaction, backed by the Development Bank of Japan, drew criticism for a price tag that exceeds the acquirer’s current market value.

Deal exceeds market value

Mitsui Chemicals and the Development Bank of Japan (DBJ) will acquire JSR from the state-backed Japan Investment Corp, according to an exchange filing reported by Reuters. Financial News in Tokyo confirmed the deal is valued at 16 trillion won.

Local media highlighted the financial weight of the move, with one report noting the acquisition cost exceeds Mitsui Chemicals' own market capitalisation of 541.22 billion JPY. The company said on Monday it would proceed with the purchase.

Stock underperforms market peers

The 13.62% drop left Mitsui Chemicals trading at 1,497 JPY, significantly underperforming the broader market. While the Nikkei 225 rose 3.4% in the same session, the chemical stock’s decline was entirely company-specific, according to Falling Shares data.

By Falling Shares' measure, the move was driven by firm-specific factors rather than market conditions. The stock has lost 28.2% over the past five days and 30.8% over the last month, placing it 37.6% below its 52-week high of 2,477.5 JPY.