Wells Fargo officially replaced the Wachovia COSI (Cost of Savings Index) with a new Wells Fargo COSI.  The initial rate is 2.40% and is reflective of the November 2009 COSI.  See http://www.moneycafe.com/library/cosi.htm for more information, including charts and graphs.

This new index is based upon the interest rates paid by Wells Fargo’s banks on certificates of deposits held by individual depositors as of the last business day of each month. This index is specific to the Wells Fargo banking group and is a weighted average of the relevant deposits. The COSI is basically reflective of the rate Wells Fargo is currently paying to individuals for their CD’s, also known as personal time deposits.  We anticipate Wells Fargo will report this rate a couple of weeks after the end of the previous month.

Prior to July 2007, this index was known as the World Savings COSI.  From July 2007 to October 2009 it was known as the Wachovia COSI.

See:
http://www.moneycafe.com/library/cosi.htm