The investor group, known as Instituto Ibero-Americano da Empresa, demanded a provisional compensation of 500 million reais ($97 million) from the company and its reference shareholders, according to a filing to the arbitration chamber of the stock exchange seen by Reuters.

A Rio court granted Americanas' bankruptcy protection request on Thursday, days after the company uncovered nearly $4 billion in accounting inconsistencies, leading to a legal feud with creditors.

According to the document filed on Thursday, the investor group claims the company's shares were priced based on their financial statements, inducing investors to error. "The acquisition of shares at a certain price, at any time in the past, was carried out with false and artificial overvaluation," they say.

Last week, Americanas Chief Executive Sergio Rial resigned less than two weeks after taking the job, citing the discovery of "accounting inconsistencies" totaling 20 billion reais ($3.87 billion).

Rial attributed the inconsistencies to differences in accounting for the financial cost of bank loans and debt with suppliers.

The investors' group filing to the arbitration chamber said that private equity firm 3G Capital was also named as responsible because the accounting consistencies "could not happen for so many years without the knowledge and tacit approval of the main shareholders."

3G Capital said it is not a direct investor in Americanas, but did not comment on the arbitration claims.

Jorge Paulo Lemann, Beto Sicupira and Marcel Telles, who are all 3G Capital founders, are shareholders in Americanas. "The board and management were chosen by 3G because they are de facto controlling shareholders in Americanas," the document says.

Americanas did not immediately respond to a request for comment.

($1 = 5.1716 reais)

(Reporting by Carolina Pulice; Editing by Rosalba O'Brien and Leslie Adler)

By Carolina Pulice