Interesting read on Bloomberg vs Symphony (through an EU policy lens, but has a lot of details about BBG business model I hadn't read elsewhere) http://www.politico.eu/article/bloomberg-vs-the-banks/
> Banks under the agency’s jurisdiction that use Symphony also agreed to store message with the messaging company for seven years and to keep duplicate copies of their decryption keys with independent custodians of their choosing.
That is true for now. But chat is trivially implemented and the monopoly only holds due to network effects. And in the last few years Bloomberg have been so arrogant with all of their clients that there is critical momentum now to migrate away the chats and have everyone bar the actual traders share terminals.
(In unrelated news, Bloomberg's recent antics pissed our firm's senior guys off enough that made a few hundred Bbg terminal users migrate to Eikon, just to send a message...)