Combined units sold is based on the number of listings sold by a company and the number of purchases through a company. (remonline.com)
ETFs combine the unit valuation system of mutual funds with the stock valuation system of equities. (policybazaar.com)
There are about 4 - 5 million worldwide combined units of PlayStation 4 and Xbox One, so it just doesn't add up for us right now. (playstationlifestyle.net)