The Instrumental Variable Identification method is revisited, in order to deal with global stability requirement, when included in adaptive control loops. It is shown that an exact symmetrized version can be introduced, permitting to work with over-dimensioned instruments. This over-determination is entailed by stability requirements, when identifying a closed loop system, using delayed input-output signals as instrument. Then, it is shown that the instrumental variable algorithm satisfies some usual conditions, permitting to garantee the global stability in the indirect adaptive control schemes.