LONDON, Jan 12 (Reuters) - Shares in British bank Barclays fell on Monday after U.S. President Trump called on Friday for a cap on credit card interest rates at 10%. 

Barclays' U.S. card operations are the ninth biggest in the market and account for around 11% of group profits, according to Hargreaves Lansdown senior equity analyst Matt Britzman.

Shares were last down 3.5% and heading for the biggest daily fall since October.

(Reporting by Samuel Indyk; Editing by Amanda Cooper)