Airbnb is reportedly raising nearly $1 billion at a sky-high $24 billion valuation

Airbnb is close to closing a nearly $1 billion funding round at a $24 billion valuation, sources tell The Wall Street Journal's Rolfe Winkler and Douglas MacMillan.

That's a heftier valuation than the enormous hotel chain Marriott (worth about $21 billion), and more than twice the valuation of the travel site Expedia.

Airbnb is earning such a gargantuan valuation with investors in part because of its sunny revenue projections: It sees itself as pulling in $10 billion in revenue by 2020, with profits of $3 billion before interest, taxes, depreciation and amortization.

Right now it expects an operating loss of about $150 million this year as it pushes to expand its services to new parts of the world and fights regulators over taxes and lodging laws.

The home rental company last raised money in April 2014 at a $10 billion valuation.