In a three-stage game in which banks can obtain liquidity through open market operations, interbank transactions or standing facilities we compare the equilibrium outcomes of fixed and variable rate tenders in the primary market. We focus on bidding behavior, induced allotment ratios, functioning of the secondary market and resorting to standing facilities, under several scenarios, among which collateral shortage and credit rationing. It is shown that overbidding is inherent to the fixed rate auction, but can be very mitigated under a variable rate procedure. Due to the existence of a finite number of equilibria, variable rate tenders allow keeping the informational content of quantity bids, as opposed to fixed rate tenders.