Polyakov founded his first bank in 1872 and by the 1890s owned an influential financial group; he was informally named "Rothschild of Moscow".

[1] Lazar remained in the shadow of his better-known brother and employer Samuel until 1872, when he founded L. S. Polyakov Bank in Moscow.

[2] Polyakov created wealth through stock-exchange deals and trading in Southern Russian step wheat.

His business rarely ventured into the textiles, metalworking, and real estate that were the fields of traditional Moscow bankers.

[2] However, the Jewish sources point at the rivalry between Polyakov and ethnic Russian bankers represented by the mayor of Moscow Nikolay Alekseyev.

[2] United Bank was chaired by an ethnic Russian appointed by the government, while Polyakov's son Alexander retained a seat on the board of directors.