Article history: Accepted 22 April 2013 JEL classification: C62 C68 D43 D21 L13 L25

Article history: Accepted 15 February 2011 JEL classification: D90 C62 O21

Article history: Accepted 30 October 2013 JEL classification: E62 O11 O41

Article history: Received 13 February 2010 Available online 1 June 2012 JEL classification: C72 D83

Article history: Received 4 April 2013 Available online 27 November 2013 JEL classification: C70 D82

Article history: Accepted 20 November 2013 Available online xxxx JEL classification: G12 G14

Article history: Received 25 April 2011 Available online 26 June 2015 JEL classification: D72 D44

Preliminary Version: Comments are most welcome. JEL classification codes: E24, J2, J4, O53

Article history: Accepted 19 December 2013 Available online xxxx JEL classification: L1 D4 C7

We examine optimal auction design when buyers may receive future outside offers. The winning bidder choose to default upon observing her offer. Under the mechanism, with highest value wins if and only is above a cutoff, winner never defaults. takes form of second-price reserve price deposit by bidder. regularity conditions, both increase distribution offers worsens. (JEL D44, D82)