On October 1st, 2015 American Express reduced the rate of transfer to British Airways from 1:1 to 1:0.8. They still continued to run transfer bonuses (50% here), today they have announced that the transfer rate will return to 1:1.
American Express made the following statement to VFTW:
Today, two of Amex’s Membership Rewards airline transfer partners, British Airways and Iberia, are increasing the transfer ratio for their rewards program, Avios. The transfer is increasing from a 5:4 to a 1:1 transfer ratio.
With this update, Amex’s Membership Rewards program now offers the most 1:1 airline transfer partners – 11 in total.
Membership Rewards now also offers Card Members the opportunity to transfer points to 21 reward program partners, which is more than any other U.S. credit card rewards program.