Symphony was formed when, in October of last year, fourteen of the world’s biggest financial-services firms, including Goldman Sachs, bought instant-messaging software company Perzo Inc and formed a new company funded by a consortium of financial firms that includes many big names —Goldman Sachs GS, +0.64% , Bank of America Corp BAC, +0.45% ., Bank of New York Mellon Corp BK, +0.46% ., BlackRock Inc. BLK, +0.68% , Citadel LLC, Citigroup Inc. C, +0.45% , Credit Suisse Group AG CS, -0.14% , Deutsche Bank AG DB, -1.01% , J.P. Morgan Chase & Co. JPM, +0.50% , Jefferies LLC, Maverick Capital Ltd., Morgan Stanley MS, +0.79% , Nomura Holdings Inc. NMR, +0.44% and Wells Fargo & Co. WFC, +0.77% .
In the context of the input sentence, determine the relationship between 'Citigroup' and 'BlackRock'.
Options: owned by, employer, distributed by, original broadcaster