Home-rental platform Airbnb is raising $1 billion in funding off an exorbitant valuation of $24 billion, according to investors speaking to The Wall Street Journal in a report published Wednesday. This valuation would hurtle the San Francisco-based service to the top of the hospitality industry. The hotel chain Marriott International, which operates more than 4,000 properties, is worth $21 billion.Airbnb's valuation is roughly double that of travel booking site Expedia, which acquired rival sites Orbitz and Travelocity earlier this year. The most lucrative hospitality business is Priceline, which has a market valuation of roughly $61 billion, and analysts expect the website to pull in $9 billion in revenue by the end of the year. Airbnb is approaching potential investors with a projected revenue of more than $900 million for this year and projections for $10 billion in revenue by 2020.