EXHIBIT 11.1

CSFB (USA), INC.  SCHEDULE OF COMPUTATION OF WEIGHTED AVERAGE NUMBER OF  COMMON SHARES AND COMMON SHARE EQUIVALENTS OUTSTANDING  AND BASIC EARNINGS PER SHARE FOR THE QUARTERS ENDED  MARCH 31, 2001 AND
2000

|                                            |                                                   | Quarters Ended March 31, |        
|------------------------------------------- | ------------------------------------------------- | ------------------------ | -------
|
|
|CSFB (USA), Inc.                            |                                                   |                          |        
|Weighted Average Common Shares:             |                                                   |                          |        
|                                            | Average Common Shares Outstanding                 |                          |        
|                                            | Average Restricted Stock Units Outstanding        |                          |        
|                                            |                                                   |                          |        
|Weighted Average Common Shares Outstanding  |                                                   |                          | 1,000  
|                                            |                                                   |                          |        
|Earnings:                                   |                                                   |                          |        
|                                            | Net Income                                        |                          | $      
|                                            | Less:  Preferred Stock Dividend Requirement       |                          |        
|                                            |                                                   |                          |        
|                                            | Earnings Applicable to Common Shares              |                          | $      
|                                            |                                                   |                          |        
|Basic Earnings Per Common Share             |                                                   | $                        | 297,806
|                                            |                                                   |                          |        
|CSFB (USA) Common Stock                     |                                                   |                          |        
|Weighted Average Common Shares:             |                                                   |                          |        
|                                            | Average Common Shares Outstanding                 |                          |        
|                                            | Average Restricted Stock Units Outstanding        |                          |        
|                                            |                                                   |                          |        
|Weighted Average Common Shares Outstanding  |                                                   |                          | 1,000  
|                                            |                                                   |                          |        
|Earnings:                                   |                                                   |                          |        
|                                            | Net Income                                        |                          | $      
|                                            | Less:  Preferred Stock Dividend Requirement       |                          |        
|                                            | Earnings Applicable to Common Shares  CSFBdirect |                          |        
|                                            |                                                   |                          |        
|Earnings Applicable to Common Shares        |                                                   | $                        | 305,229
|                                            |                                                   |                          |        
|Basic Earnings Per Common Share             |                                                   | $                        | 305,229
|                                            |                                                   |                          |        
|CSFBdirectCommon Stock                      |                                                   |                          |        
|Weighted Average Common Shares:             |                                                   |                          |        
|                                            | Average Common Shares Outstanding                 |                          |        
|Earnings:                                   |                                                   |                          |        
|                                            | Net Income (Loss)                                 |                          | $      
|                                            |                                                   |                          |        
|Earnings (Loss) Applicable to Common Shares |                                                   | $                        | (7,423 
|                                            |                                                   |                          |        
|Basic Earnings (Loss) Per Common Share      |                                                   | $                        | (0.40  
|                                            |                                                   |                          |        

---

QuickLinks