How do financial institutions buy and sell shares?

Hi guys,

how do financial institutions actually execute trades? I know that they usually make use of block trades since they tend to trade in big amounts, but how does that actually happen? Is there a type of software that all financial institutions use just like the Bloomberg terminal or Eikon that they use for financial data?  How do they research potential investment opportunities? And are there any books that y´all could recommend regarding that topic?

Thank you