Staggered by losses despite two federal rescues, Citigroup is accelerating moves to dismantle parts of its troubled financial empire in an effort to placate regulators and its anxious investors.

Under pressure from Washington and Wall Street, the financial giant plans to split itself in two, people with knowledge of the plan said on Tuesday, heralding the end of the landmark merger that created the bank a decade ago.

Citigroup, which originally planned to sell in coming years the businesses it no longer deemed central, is speeding up the process to mitigate potentially billions of new losses as the economy worsens, these people said. The government, which has twice supplied it with taxpayer support during the financial crisis, wants to avoid a repeat, said another person with knowledge of the situation.

But some Wall Street analysts and investors questioned whether the plan, which included the announcement on Tuesday that it would split off its prized Smith Barney brokerage, goes far enough to address Citigroup’s immediate troubles.