After the close Boardwalk Partners announced a public offering of stock. Thats why the stock dropped in the last 30 minutes by a buck and change.

Btw lately mlps that have done stock offerings have seen their stocks sell-off only slightly as demand for yield here appears to be very strong. Check Buckeye Partners (BPL) which did an offering in the last 2 weeks and the stock price is holding close to 50.