Sergei Yurievich Polonsky (Russian: ?????? ??????? ?????????, born 1 December 1972) is a Russian businessman.
He is the owner and head of one of the largest real estate companies in Russia, Mirax Group (2004–2011).
He was one of the richest men in Russia before the late-2000s financial crisis.
Now, he is a shareholder and investor in a number of commercial structures incorporated by the holding company Potok.
He is currently awaiting trial in Moscow on charges of fraud.
On 12 July 2017 he was found guilty, but the judge ruled that too much time had passed since the crime was committed for the court's decision to be implemented.