1MERGE dbo.MyTarget targ
2USING (SELECT ... FROM dbo.MySource GROUP BY .....) src
3ON (targ.Identifier = src.Identifier
4 AND targ.Name = src.ConstituentName
5 AND targ.Ticker = src.ConstituentTicker
6 AND (targ.CUSIP = src.CUSIP OR targ.ISIN = src.ISIN OR targ.SEDOL = src.SEDOL))
7WHEN MATCHED THEN
8-- update values
9;