Shares of Barry Diller’s IAC/InterActiveCorp took a hit Tuesday as the company said fourth-quarter profit plunged 85% to $16.7 million.In the variegated world of IAC, the dip came from a $214 million writedown on the company’s so-called discount biz, including entertainment coupon books. The stock fell nearly 4% in early trading. It ended the day down 1.60% at $38.64. Revenue rose in all divisions, up a total of 8% to $1.82 billion, IAC said. And excluding the charge, profits beat Wall Street’s expectations. IAC’s diverse assets include HSN, Ticketmaster and a roster of online businesses such as Ask.com, CitySearch, Evite, Match.com, Gifts.com and Lending Tree.