Nomura Holdings Inc.'s latest attempt to revamp its international business is falling flat with investors, who have never been so downbeat on the stock relative to global peers.

Japan's largest brokerage has dropped almost 3 percent in Tokyo trading since Chief Executive Officer Koji Nagai unveiled a sweeping overhaul plan on April 4, bringing its six-month slide to 23 percent. That's the second-biggest decline among major securities firms worldwide after Societe Generale SA, outpacing even notoriously poor performers like Deutsche Bank AG. Nomura's valuation discount versus global financial companies deepened to 58 percent this week, the widest gap since Bloomberg began tracking the data in 1999.

The figures underscore entrenched skepticism over Nagai's plans to revive a business buffeted by years of stop-start international expansions and an increasingly competitive battle for retail traders in Japan. While valuations this low have foreshadowed past rallies for Nomura, some investors are losing patience after watching the stock tumble more than 70 percent since the ill-fated takeover of Lehman Brothers Holdings Inc.'s European and Asian operations in 2008.