After markets closed Thursday, the federal government revealed details of the planned sale of its 19% stake in Petro-Canada, setting the stage for the biggest single share sale in Canadian history.

The offering, estimated to be worth $3 billion, is expected to close by Sept. 29. Ottawa intends to sell all of its 49.4 million shares to investors in Canada, the United States and internationally.

A third of the stake will likely go to Canadian retail invetors, while the rest will be sold to institutional investors in Canada and the U.S.

Before the announcement Petro-Canada shares closed down $1.22 at $61.65.

In Friday’s morning trading Petro-Canada shares were up 15¢ to $61.80.

The Petro-Canada share sale will be handled by 22 underwriters, led by CIBC World Markets and RBC Dominion Securities in Canada.

The syndicate also includes smaller Canadian firms including Calgary-based FirstEnergy Capital and Peters & Co.

In the United States, Merrill Lynch will handle the share disposition.