...LONDON (Standard & Poor's) May 29, 2015--Standard & Poor's Ratings Services said today that it had assigned its 'B+' long-term issue rating to the proposed fixed-rate reset perpetual additional Tier 1 (AT1) capital securities to be issued by Santander UK Group Holdings PLC (SanUK HoldCo; ###/Stable/A-2). The rating is subject to our review of the notes' final documentation. These notes constitute the Santander U.K. group's first public issuance of AT1 instruments and the first public issuance from SanUK HoldCo, the newly established U.K. nonoperating holding company. In 2014, SanUK HoldCo issued two similar additional Tier 1 instruments for a total amount of ú800 million to its parent, Banco Santander. We are assigning ratings to these notes in accordance with our criteria for hybrid capital instruments (see "Bank Hybrid Capital And Nondeferrable Subordinated Debt Methodology And Assumptions," published Jan. 29, 2015). The 'B+' issue rating reflects our assessment of Santander UK's unsupported...