The issue with WhatsApp is that it never had a sustainable business model. First it was free with the hope of monetizing. Then it was free for a year, but a buck afterwards (pretty good if you ask me). Then WhatsApp found many users could partake of the e-economy due to lacking debit/credit cards, so it went back to free with some idea of Corporate relationships paying for things. (http://www.investopedia.com/articles/personal-finance/040915...)

While Yahoo has been stagnant, it makes money.