It said Sprott had agreed to invest C$3 million and acquire 10 million of the 10.5 million units on offer, in a non-brokered private placement priced at 30c which was designed to raise $3.15 million.
"His investment makes him the largest single investor in the company and is a strong endorsement of our ongoing efforts to increase our gold resource at the Herbert gold project in southeast Alaska, where we are currently conducting a drill programme," president and CEO Ian Klassen said.
The company had announced a high-grade resource in 2019 for Herbert, comprising an indicated 1.88 million tonnes at 10.03g/t for 606,500 ounces and an inferred 553,429t at 14.15g/t for 251,700oz.
Grande Portage said last week it intended to drill 18-20 holes from up to four different platforms, to test up to four separate major veins and their satellite structures at Herbert this summer.
It said it was using two 12-hour shifts per day and was observing protocols and the evolving COVID-19 situation, and would proactively act to protect the health of its workforce.
Herbert lies 25km north of Juneau.
In a presentation this month, Grande Portage said it was also aiming to acquire permits to drill underground and conduct a 50,000t bulk sample.
The company had last raised about $500,000 at 12c per unit in February.
Its shares (TSX: GPG) touched 59c intraday, a level last seen in October 2017.
They closed up 65.7% to 58c, capitalising it about $39 million (US$29 million).