It was a result that forced the ouster of the British Prime Minister, sent shockwaves across financial markets and raised doubts over the fate and composition of the European Union.
Just how did experts get it this wrong?
The U.K. EU referendum vote prompted a global massive market selloff as markets were priced in expecting a remain outcome. More than two trillion dollars were wiped out globally, the largest drop on record.
Leading up to voting day, the vast majority of polls predicted the remain side would prevail, however the final results gave the leave side a victory margin of more than one million votes.
According to SurveyMonkey's Chief Research Officer, Jon Cohen, young voter turnout and the death of Lawmaker Jo Cox are the likely largest factors in the discrepancy between polls and the final outcome.
"The Remain campaign was heavily dependent on support among younger voters and they simply didn't show up," Cohen told CNBC.
The murder of Cox in the days leading up to the vote, triggered new challenges in polling, even though it was difficult to determine how the tragedy would influence polling.
"After the assassination, the Remain side became more vocal and were willing to share their opinions about Brexit than were leave voters," Cohen said. "It was a very difficult environment to gauge an opinion in."