MAST THERAPEUTICS INC

CUSIP: 576314108 Class: COM

OCONNOR, A Distinct Business Unit of UBS ASSET MANAGEMENT AM's Holding History (CIK: 0001132716)

Note: Option positions (PUT/CALL) are excluded.

Q4 2013
Shares 99,800 Value ($000) $46,000 Avg Close — Range —
Q3 2013
Shares 200,000 Value ($000) $88,000 Avg Close — Range —
Q2 2013
Shares 794,900 Value ($000) $341,000 Avg Close — Range —