The announcement of a potential sale of up to $50M in ATM shares by Cardlytics could have a neutral to slightly positive impact on its stock price in the short term. The move indicates a strategy to increase liquidity, which can be positive, but the dilutive effect of issuing new shares might offset some of the potential gains. The involvement of reputable financial institutions such as Evercore, BofA Securities, and Cantor Fitzgerald could add credibility to the transaction, potentially mitigating negative market reactions.