Overnight Microsoft issued a bad code update to its server but failed to stop the update going live once they realize the faulty code, which in turn bright down Bing and Yahoo as well as Siri and Cortana.
Apparently was able to eventually stop the code from reaching beyond a set group of servers by getting ahead of it and turning them off since it was unable to recall or stop the code propagation.
This, in turn, caused a cascading effect for both Bing and Yahoo search engines. Yahoo runs off Microsoft servers. Once the errors were caught and quarantined, Microsoft turned back on its servers, but then Yahoo remained down due to the pile-up of the unserved search request that piled up.
According to reports, Hotmail was also down briefly.
Google search and services were unaffected by the outages.