Citigroup

(C) - Get Report

will reportedly pay a fine of $300 million to $350 million and be forced to make a public apology to settle allegations it issued misleading stock research during the late-1990s bull market.

A broader settlement encompassing most of Wall Street is proving more elusive, however, as smaller firms like

Lehman

(LEH)

and

Bear Stearns

(BSC)

argue they shouldn't be tarred with the same brush as their larger rivals,

The Wall Street Journal

reported.

Citi could pay up to an additional $100 million to fund independent stock research, a controversial solution to the problem of conflicts of interest among analysts at big firms that is nevertheless still on the table. In all, Wall Street faces some $1 billion in settlement payments in the investigation, which is being headed by New York Attorney General Eliot Spitzer.

The probe into Citigroup has so far found no evidence that CEO Sandy Weill was aware that research at its Salomon Smith Barney unit might have been tainted by a desire to lure investment banking clients, the newspaper said. Weill has conceded he asked former telecom analyst Jack Grubman to take a "fresh look" at

AT&T

(T) - Get Report

before an upgrade, but investigators haven't found any smoking gun to show Weill had reason to believe the upgrade wasn't valid. Salomon received a lucrative underwriting pact from AT&T shortly after Grubman changed his rating.

It also remained unclear whether a public apology would have to come from Citigroup or Weill himself.