The scrolling animation / progress indicator thingy on your blog seems broken by the way. It quickly moves out of the visible view on a pretty normal setup (24" FHD screen, Linux, Firefox).
Financial data, as in a time series of prices? It really depends on your budget, desired overhead, and amount of data. Some funds store data in flat files (broken down by date, instrument, ticker, etc), others use time series databases, such as ClickHouse or Kdb+. Using flat files is probably the simplest and most cost effective while still enabling you to store a massive amount of data, but using a database obviously enables querying and analytics.