Barnes & Noble split itself into two separately, publicly-owned companies on Monday. Shares in the retail bookseller began trading at about 65 percent of the value of the previously combined operations, with a market cap of about $1.3 billion, while shares at Barnes & Noble Education dropped below their “when issued” trading level from last week, priced at around $12.65 a share in early morning trading. (With fewer shares outstanding than BKS, BNED is pointing to a market cap of a little over $600 million.)