I plead innocent. Having passed up the bottom 4 on yahoo's "institutional holder" list but not having the resources of an institution, it would take a tempting price to get me back for a second (or is it third, fourth--I can't remember...) helping.
Heh. Just curious. My first guess is the company itself actually. For the past month or so (until this week) somebody bought like a pigdog, averaging say 2000 shares per day beyond the previous level, regardless of price increases. Then suddenly that extra volume switched off again. Smells a little like corporate trading to me.