New York (CNN Business) Altria hopes pot is the key to help it grow beyond its stagnant cigarette business.

Tobacco giant Altria is investing $1.8 billion in Canadian cannabis company Cronos Group. That will give Altria a 45% stake in the company, with an option for Altria to increase its stake to 55% over the next five years.

Reports of an Altria-Cronos deal first surfaced earlier this week . The decision by Altria to go ahead with an investment in Cronos shows that Altria is serious about investing in marijuana as a new growth area as sales of traditional cigarettes slow.

Altria's stock has fallen nearly 25% this year and the company is expected to report revenue growth of only about 1% this year and in 2019.

"Investing in Cronos Group as our exclusive partner in the emerging global cannabis category represents an exciting new growth opportunity for Altria," said Howard Willard, Altria's CEO, in a statement.