On Wall Street, the rich may get still richer.

Investment bankers and many traders may see bonuses rise 15 percent from elevated 2006 levels, as profitability grows from international operations, proprietary trading and derivatives, according to a study released on Tuesday by Johnson Associates Inc., a prominent compensation consultant in New York.

Incentive pay on Wall Street for workers in the private equity sphere may rise 20 percent or more, the study said, as low borrowing costs fuel record buyout activity.

Goldman Sachs Group Inc. (GS) in April closed a $20 billion fund, while Blackstone Group , which is preparing to go public, said it has raised $19.6 billion for its latest fund.

Not all financial services workers will benefit equally. Retail banking employees may see incentive pay unchanged to up just 5 percent, the study said, as rising defaults and the U.S. housing slowdown crimp profit.

Incentives can comprise the bulk of compensation for top investment bankers and traders. Their overall pay regularly reaches seven-figure, and occasionally eight-figure, levels.

Bonuses for securities industry employees were projected last year to have risen 17 percent to a record $23.9 billion, according to a December estimate by former New York State Comptroller Alan Hevesi.

Johnson Associates was unavailable for immediate further comment.