The Province of Ontario earned more than it expected from its recent initial public offering of Hydro One on stock markets, bringing the total financial gain to public coffers for monetizing the power utility to $5 billion — and counting.

Hydro One said Thursday said the deal's underwriters exercised their right to sell more shares in the company than first anticipated, known as an "over-allotment option."

All in all, the government was able to sell 89,250,000 shares in the utility to the public at an IPO price of $20.50 per share. That's almost nine million more shares than first anticipated.

The shares were trading slightly above that level, changing hands at around $22 per share on the TSX on Thursday.

The over-allotment bumped up the proceeds of the IPO by $167 million to $1.83 billion. The province also gained about $2.2 billion from a deferred tax asset benefit and another $1 billion from a special dividend and payments-in-lieu of taxes, bringing the total financial gain to more than $5 billion.

That's more than halfway to the total the province hopes to raise from privatizing the utility, which is $9 billion, to come via several more chunks of stock offerings. The province says it will retain 40 per cent of Hydro One when all is said and done and no one investor will be allowed to own more than 10 per cent, ensuring that the province can always retain control even as it sells off most of its ownership.

The utility is saddled with $8.3 billion in debt accrued when the old Ontario Hydro was broken up into five separate utilities, including Hydro One. Most of what Ontario earns from selling the company off will be used to pay down that debt. The remainder will go to fund infrastructure projects, the province says.

Hydro One owns $23 billion in assets and took in $6 billion in revenue last year.

