Topping the list: Blood of Bahamut, a DS RPG released by Square Enix on August 6, just a few weeks after Dragon Quest IX. No mystery why that one didn't sell! Monster Hunter Tri, which may be more surprising, was the blogger's number two choice, due to low margins on the standard edition, as well as some unspecified shipping issues from Capcom.
The full list of what one retailer believes was unprofitable in 2009 is after the break. It features a few more big names, like Sonic, Mario, and Gran Turismo. The preponderance of major games is probably due to the fact that retailers stocked way more of the big games, expecting more sales, and stocked presumably niche titles more judiciously.