Facebook Inc warned on Tuesday of a dramatic increase in spending in 2015 and projected a slowdown in revenue growth this quarter, slicing a tenth off its market value. With Facebook’s mobile advertising business delivering repeated quarters of breakneck revenue growth, the company has faced little pushback from investors on pricey, multi-billion dollar acquisitions such as WhatsApp and Oculus. Shares of Facebook reached an all-time high of $81.16 on Tuesday, before the company reported its third-quarter results.