While Arsenal's window has been positive overall, Arsene Wenger failed to land a top-class defender to strengthen a vulnerable back line.
The Gunners made an effort to bring Jonny Evans to the Emirates late in the day but West Brom deemed their £12m offer to be derisory.
The Baggies could lose the Northern Ireland international for just £3m in the summer if they are relegated, though the addition of Daniel Sturridge on loan from Liverpool should help their task to survive.