Currently oil and gas stocks represent 6% of its index. : An unidentified oil worker walks in front of a natural gas flame burning off in the Persian Gulf desert oil field of Sakhir, Bahrain. AP/Hasan Jamali (Reuters) - Norway's trillion-dollar sovereign wealth fund is proposing to drop oil and gas companies from its benchmark index, which would mean cutting its investments in those companies, the deputy central bank chief supervising the fund told Reuters, sending energy stocks lower.