What is a suitable,stable, high performing database for Large Financial Time Series Data?
In my opinion you must be, or you need, a DBA.
Not a single rdbms can solve problems with big data out of the box.

In your case partitions can be useful for example. So data compression, etc...

I can just suggest 3 alternatives:


SQL Server Enterprise Edition
Oracle Enterprise Edition
Postgresql


And the skills to manage data.