Build America Bonds (BABs) were issued by municipalities for 20 months as a part of the 2009 fiscal package. Unlike traditional tax-exempt municipals, BABs are taxable to the holder, but the Treasury rebates 35% of the coupon to the issuer. The stated purpose was to provide municipalities access to a more liquid market including foreign, tax-exempt, and tax-deferred investors. We find BABs do not exhibit greater liquidity than traditional municipals. BABs are more underpriced initially, particularly for interdealer trades. BABs also show a substitution from underwriter fees toward more underpricing, suggesting that the underpricing is a strategic response to the tax subsidy.