Barnes & Noble stock has sunk so low again that investor Bill Ackman of Pershing Square–who lost a considerable sum on his company’s 37 percent stake in Borders–has returned to the scene with a provocative offer. Ackman still thinks there is financial reason to put the two big bookselling chains together, likely as a salvage route for Borders more than anything, and indicates he will finance a $16 a share takeover offer for the smaller, weaker Borders to buyout BN. The theoretical offer was declared in an SEC filing saying his companies “would be prepared to finance, on mutually acceptable […]