(Adds details on offering, background)
By John Tilak and Euan Rocha
TORONTO, Oct 28 (Reuters) - Ontario electric utility Hydro One Ltd's initial public offering is set to price at the high end of its earlier disclosed range, according to three sources familiar with the matter.
The company is likely to tighten the offering price range to C$20 to C$21 per share, from the C$19 to C$21 per share range it had announced earlier, said the sources, who spoke on condition of anonymity.
The share offering, for a stake of roughly 15 percent in the province's largest electric utility, is being significantly oversubscribed, one of the sources said.
The Hydro One IPO could be one of the biggest initial public offerings in Canadian history. The last large IPO in Canada was PrairieSky Royalty Ltd's C$1.67 billion offering last spring, according to Thomson Reuters data.
Earlier this month, the government of Ontario outlined plans to sell up to 89.25 million Hydro One shares in an IPO that was seen pricing in the range of C$19 to C$21 a share, pegging the overall value of the company between C$11.31 billion ($8.57 billion) and C$12.5 billion ($9.48 billion).
Royal Bank of Canada and its smaller rival Bank of Nova Scotia are the lead underwriters on the deal.
Other institutions including BMO, CIBC, TD Securities, National Bank Financial, Desjardins Securities, Raymond James, GMP Securities, Barclays, Goldman Sachs and Credit Suisse are also involved in the offering.
The IPO as it stands will raise C$1.87 billion if it prices at the top end of a C$20 to C$21 range and if the bookrunners on the IPO tap an over-allotment option tied to the offering. ($1 = 1.3191 Canadian dollars) (Reporting by John Tilak and Euan Rocha; Editing by Alan Crosby and Matthew Lewis)