Anchor for a vertical formwork comprising - a fixed part suitable for being fixed to a formwork panel and - fixing means for fixing said fixed part to the formwork panel, - the fixing means comprising a fixing key arranged in a fixing housing of the fixed part, said fixing key being configured for being housed in a hole of a supporting wall of the formwork panel, and - the fixed part comprising a pin suitable for being housed in a second hole of the supporting wall of the formwork panel, characterized in that - the pin comprises a lateral groove, and - the fixing key comprises an off-centered stop with respect to the axis of rotation of the fixing key, such that in a first angular position the off-centered stop of the fixing key can be introduced in the hole of the formwork panel, and in a second angular position the off-centered stop is retained by the formwork panel and therefore the anchor is fixed to the formwork panel, - the fixing key comprising a cam that is configured to rest on a supporting surface of the hole of the supporting wall that can be traversed by said fixing key, the distance from the axis of rotation of the fixing key to said supporting surface being greater when said fixing key is in the second angular position than the distance (d) from said axis of rotation to said supporting surface when the fixing key is in the first angular position, so that the anchor is configured to move upward when the fixing key turns from the first angular position to the second angular position, such that the supporting wall can enter the groove of the pin when the anchor moves upward, so said pin can be retained by said supporting wall when the fixing key is in said second angular position. - a fixed part suitable for being fixed to a formwork panel and - fixing means for fixing said fixed part to the formwork panel, - the fixing means comprising a fixing key arranged in a fixing housing of the fixed part, said fixing key being configured for being housed in a hole of a supporting wall of the formwork panel, and - the fixed part comprising a pin suitable for being housed in a second hole of the supporting wall of the formwork panel, - the pin comprises a lateral groove, and - the fixing key comprises an off-centered stop with respect to the axis of rotation of the fixing key, such that in a first angular position the off-centered stop of the fixing key can be introduced in the hole of the formwork panel, and in a second angular position the off-centered stop is retained by the formwork panel and therefore the anchor is fixed to the formwork panel, - the fixing key comprising a cam that is configured to rest on a supporting surface of the hole of the supporting wall that can be traversed by said fixing key, the distance from the axis of rotation of the fixing key to said supporting surface being greater when said fixing key is in the second angular position than the distance (d) from said axis of rotation to said supporting surface when the fixing key is in the first angular position, so that the anchor is configured to move upward when the fixing key turns from the first angular position to the second angular position, such that the supporting wall can enter the groove of the pin when the anchor moves upward, so said pin can be retained by said supporting wall when the fixing key is in said second angular position.