(For a Reuters live blog on U.S., UK and European stock markets, click LIVE/ or type LIVE/ in a news window) * Both FTSE 100 and FTSE 250 flat May 21 (Reuters) - London’s FTSE 100 was flat on Friday as weakness in banks countered a bigger-than-expected jump in retail sales, while Card Factory fell after reporting a slight dip in store sales. The blue-chip index was flat, with banks including HSBC Holdings, Prudential Plc and Standard Chartered being the biggest drag. Miners including Anglo American Plc, Glencore Plc and Rio Tinto fell between 0.2% and 0.6%. The domestically focussed mid-cap FTSE 250 index was also flat. Retail sales surged by 9.2% in April, when non-essential shops reopened after months of closure due to COVID-19 restrictions, their biggest jump since a previous reopening in June, official data showed. Britain’s biggest seller of building materials, Travis Perkins, rose 1.7% after selling its plumbing and heating business to an affiliate of investment firm H.I.G. Capital for 325 million pounds ($461 million). Card Factory slid 7.2% after reporting a marginal drop in like-for-like store sales, compared with 2019, after the UK began reopening stores and eased restrictions in April. (Reporting by Shivani Kumaresan in Bengaluru; Editing by Subhranshu Sahu) Our Standards: The Thomson Reuters Trust Principles.