The book retailer’s down 9.4% to $16.85 this morning after Chairman Leonard Riggio disclosed in an SEC filing that he unloaded 3.7M shares yesterday for an average of $17.30 apiece in a privately negotiated block trade. He says that he made the $64M deal “for long-term financial and estate planning purposes.” He still has 20.1% of the company’s stock, about 12.1M shares, making him “the Company’s largest shareholder, a position I feel very good about,” he said in a release. “I love this company and I believe in its future as I do in all of the wonderful people who work here.” It’s easy to understand why he’s so defensive: This is the second major stock sale by a Barnes & Noble insider this month: Earlier John Malone’s Liberty Media unloaded 90% of his stake. He picked up 17% of the company for $204M three years ago when he wanted to buy the retail chain. B&N’s stock price is down 24% over the last 30 days.