New York ? Bristol-Myers Squibb Co. lowered its profits by nearly $1 billion Monday for 1999 through 2001 because of questionable sales practices now under investigation by prosecutors and regulators.

At issue is a program of sales incentives the drugmaker set up for wholesalers. The program was created to boost sales and meet revenue and earnings projections, but it left wholesalers with swollen inventories.

The pharmaceutical company restated its earnings for 3 1/2 years, lowering its profit from continuing operations by $900 million and sales by $2.5 billion for the years 1999, 2000 and 2001. But it raised profit by $200 million and sales by $653 million for the first six months of 2002.

The Securities and Exchange Commission and federal prosecutors are investigating the sales practices. Monday’s disclosures also could lead to a flood of new lawsuits from shareholders angry that the company deceived them.