SUPPLEMENT DATED AUGUST 10, 2010

TO PROSPECTUSES DATED APRIL 30, 2010

FOR KEYPORT LATITUDE AND KEYPORT CHARTER

AND

TO PROSPECTUS DATED APRIL 30, 2004

FOR KEYPORT VISTA

ISSUED BY SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

KEYPORT VARIABLE ACCOUNT A

The name of the advisor to the Rydex Funds has been changed from PADCO Advisors II, Inc. to Rydex Advisors II, LLC.

Please retain this supplement with your prospectus for future reference.

Latitude, Charter, Vista (US) 8/2010