BlackRock Inc. is the world's biggest money manager. The company had bought shares in OGX Petroleo & Gas Participacoes SA this week. This was after the worst crude oil producer had increased its presence in Brazil's benchmark index.

According to a data compiled by Bloomberg, the BlackRock Brasil Gestora de Investimentos Ltd. unit purchased 93.5 million OGX shares. The data filed September 3 also showed that the purchased shares were for its exchange traded fund. The said shares were valued USD16.8 million based on September 3 closing trade prices.

According to the company's report, OGX founder Eike Batista had sold 177.2 million shares from August 29 to September 3. The move for the sale was after the billionaire looked to raise capital to pay off debt. The proceeds of the sale would also be used to boost some of his energy startups. Batista's wealth decreased more than USD30 billion over the past 16 months according to Bloomberg's Billionaires Index.