Historical clue formulations

• Half of a stock market index name — 2018-05-19
• Standard & ___ — 2018-01-20
• Standard partner — 2008-12-14
• Standard partner — 2006-04-07
• Standard & ___ — 2000-02-13
• Standard's partner — 1998-12-18
• Standard partner — 1998-05-27