Mizuho Shares Slide on Rakuten Bank Investment Uncertainty

CNBC reported Monday that shares of Mizuho Financial Group plunged as much as 7.7% after the Japanese bank said it had not finalized any decision regarding a potential investment in Rakuten Bank. The clarification came in response to a weekend news report that rattled investors and briefly sent ripples across Tokyo-listed financial stocks.

Media Report Triggers Sharp Market Reaction

Japanese newspaper Yomiuri Shimbun reported Sunday that Mizuho planned to exit its existing stake in Rakuten Card Co. and redirect that capital into Rakuten Bank instead. The report cited unnamed informed sources. Mizuho currently holds a 14.99% stake in Rakuten Card, the credit card and financial services arm of internet and e-commerce conglomerate Rakuten Group. Yomiuri also reported that a separate 49% stake held by Mizuho Securities in Rakuten Securities would remain untouched. Mizuho pushed back quickly, acknowledging only that it was exploring various options, including the possibility of a Rakuten Bank investment, while stressing that no decision had been reached.

Background: Rakuten Fintech Restructuring in Progress

The report lands at a sensitive moment for Rakuten’s financial operations. Analysts at Jefferies noted that Rakuten Group’s fintech segment is currently undergoing a broad reorganization, with a completion date set for October 2026. Under that plan, Rakuten Bank, Rakuten Card, and Rakuten Securities would be consolidated into a single group structure. Jefferies flagged a key risk in the process: Rakuten Bank could end up overpaying to absorb its card and securities units. Direct involvement by Mizuho, the analysts suggested, could help prevent that outcome and inject discipline into the consolidation.

Mizuho’s Strong Earnings Offer Little Buffer

The selloff came despite a blowout quarterly earnings report from Mizuho. The bank posted a staggering 660% year-on-year surge in fourth-quarter net profit, with earnings reaching 228.7 billion yen, roughly $1.44 billion, for the quarter ending March 2026. That compared with just 30.1 billion yen in the same period a year earlier. The bank attributed the jump to robust growth in fee-based business lines and the benefit of higher interest rates following recent policy adjustments by the Bank of Japan. Strong fundamentals, however, were not enough to reassure markets rattled by strategic ambiguity.

Rakuten Bank Rises as Mizuho Falls

While Mizuho’s shares closed roughly 7.2% lower, Rakuten Bank moved sharply in the opposite direction, gaining more than 8% on the session. The divergence reflects market speculation that any Mizuho involvement could benefit Rakuten Bank’s standalone valuation. Analysts expect Mizuho to provide further clarity on its intentions ahead of the October restructuring deadline.

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