wirehouse

Etymology
1904,, from earlier (1894). Originally referred to brokerage companies that owned or leased telegraph lines, so that market information could be transmitted more quickly. Later generalized to “major brokerage”. Wirehouses are now defined by that they have a direct access to "Fed-Fund Wires", which is the system in which all banks and only the big brokerage houses can "wire" money directly from one account to another. Smaller brokerage firms do not have their own wire line, but need to send transactions by transmitting them through a bank's wire system.

Noun

 * 1)  A major brokerage company, generally nationwide, with multiple branches.
 * 2) * 2012, Josh Brown, “Perhaps I’ve Been a Bit Too Harsh…”,  Financial Adviser, January 25, 2012:
 * Ten years ago, the Wall Street wirehouse brokerage firm seemed unassailable – part of the very firmament underpinning the entire investment industry from coast to coast.
 * 1)  A brokerage company with a telegraph line, telephone line, or electronic communication network.
 * 2) * 1904, N.Y. Evening Post 18 June, 1904 (Financial Section) 1/7
 * The so-called ‘wire house’ …is a product of the boom times.

Usage notes
In contemporary use generally used narrowly, referring specifically to the Big 4 retail brokerage firms operating in the US: Wealth Management,, , and  & Co. In looser usage, applied to any large brokerage.