MBIA Inc. fell the most in 11 months after the bond insurer said a regulator hasn't decided whether to allow a unit that backed soured mortgage debt to make an interest payment on notes.

The insurer dropped as much as 12 percent to $9.35 before climbing back to $9.48 as of 10:39 a.m. in New York. The shares have declined 18 percent this year.

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