The trading terminal, which is used by hundreds of thousands of people around the world, went down on Friday morning (London time).
The problem, which affected traders worldwide, effectively brought the sector to halt for at least half of the day, with sources telling City A.M. “The City is on hold – no one is doing anything.”
The Treasury was forced to delay the issue of a £3bn bill tender as a result, although it was rescheduled for this afternoon.
Other deals are thought to have also been delayed or scuppered and trading volumes are expected to be significantly down, as workers left their offices in droves.
It wasn't until gone 4pm that Bloomberg confirmed service had been fully restored.
The FCA told City A.M. it was now looking to ascertain the effect it had on the companies it regulates. A spokeswoman said: "We are aware of the issue and are monitoring the impact on our firms.”
She declined to comment on whether there would be an investigation into the matter or whether Bloomberg could be fined as a result.
People on Twitter certainly think it was a Big Deal.
Millions of traders are looking out the window for the first time in years. #BloombergDown— Lou Whiteman (@louwhiteman) April 17, 2015
Bloomberg terminals are down globally, we may as well cancel Friday and start the weekend now #bloombergdown— Andy (@TNT_Master19) April 17, 2015
A Bloomberg spokesman said: "Service has been fully restored.
"We experienced a combination of hardware and software failures in the network, which caused an excessive volume of network traffic. This led to customer disconnections as a result of the machines being overwhelmed. We discovered the root cause quickly, isolated the faulty hardware, and restarted the software.
"We are reviewing our multiple redundant systems, which failed to prevent this disruption."