diff --git a/src/proto_alpha/lib_protocol/delegate_storage.ml b/src/proto_alpha/lib_protocol/delegate_storage.ml
index b2ee0bfdc66e820dd87d20e0232a5b71ebc5e400..04ee724eba8d941c73970d9882645579780422f4 100644
--- a/src/proto_alpha/lib_protocol/delegate_storage.ml
+++ b/src/proto_alpha/lib_protocol/delegate_storage.ml
@@ -25,6 +25,25 @@
 (*                                                                           *)
 (*****************************************************************************)
 
+(*
+  Some invariants:
+
+  A contract is a delegate <=>
+    - it is registered (i.e. in the set {!Storage.Delegates.mem}), and
+    - its full staking balance is initialized.
+
+  If a contract is a delegate then :
+    - it has no stake in another account, though it may (still) have unstake
+        requests from another contract.
+
+  If a contract is not a delegate then:
+    - it has no *own* frozen stake (a.k.a. frozen deposits),
+    - it has no consensus key.
+
+  Once a contract has become a delegate, it is so forever. There are no ways
+  to unregister.
+*)
+
 type error +=
   | (* `Permanent *) Unregistered_delegate of Signature.Public_key_hash.t
 
@@ -129,7 +148,11 @@ module Contract = struct
       in
       let* c = Contract_delegate_storage.set c contract delegate in
       let* c =
-        Stake_storage.add_delegated_stake c delegate balance_and_frozen_bonds
+        (* Initializes the full staking balance of [delegate]. *)
+        Stake_storage.initialize_delegate
+          c
+          delegate
+          ~delegated:balance_and_frozen_bonds
       in
       let*! c = Storage.Delegates.add c delegate in
       let* c = Delegate_consensus_key.init c delegate pk in
diff --git a/src/proto_alpha/lib_protocol/full_staking_balance_repr.ml b/src/proto_alpha/lib_protocol/full_staking_balance_repr.ml
index 745ed009b166b5c0be8595a5cfc64c8d8d752a10..1d0e825c5522470edd890c4860db08c6f903ee56 100644
--- a/src/proto_alpha/lib_protocol/full_staking_balance_repr.ml
+++ b/src/proto_alpha/lib_protocol/full_staking_balance_repr.ml
@@ -14,12 +14,6 @@ type t = {
 let make ~own_frozen ~staked_frozen ~delegated =
   {own_frozen; staked_frozen; delegated}
 
-let zero =
-  make
-    ~own_frozen:Tez_repr.zero
-    ~staked_frozen:Tez_repr.zero
-    ~delegated:Tez_repr.zero
-
 let encoding =
   let open Data_encoding in
   conv
diff --git a/src/proto_alpha/lib_protocol/full_staking_balance_repr.mli b/src/proto_alpha/lib_protocol/full_staking_balance_repr.mli
index 019ab5cf08ad568a40c4f6360455c6f37fe15cd7..0fde0fbfd3ec279e897f724cc6c32a0ff1eef609 100644
--- a/src/proto_alpha/lib_protocol/full_staking_balance_repr.mli
+++ b/src/proto_alpha/lib_protocol/full_staking_balance_repr.mli
@@ -14,8 +14,6 @@ type t = private {
 val make :
   own_frozen:Tez_repr.t -> staked_frozen:Tez_repr.t -> delegated:Tez_repr.t -> t
 
-val zero : t
-
 val encoding : t Data_encoding.t
 
 (** The weight of a delegate used for voting rights. *)
diff --git a/src/proto_alpha/lib_protocol/stake_storage.ml b/src/proto_alpha/lib_protocol/stake_storage.ml
index 1cbe43ee1bc47020a9353548d694f27c74a76e26..bd3255e5c265f3d0b6ad131cc17714042da608ea 100644
--- a/src/proto_alpha/lib_protocol/stake_storage.ml
+++ b/src/proto_alpha/lib_protocol/stake_storage.ml
@@ -73,20 +73,7 @@ module Selected_distribution_for_cycle = struct
     Storage.Stake.Selected_distribution_for_cycle.remove_existing ctxt cycle
 end
 
-let get_full_staking_balance ctxt delegate =
-  let open Lwt_result_syntax in
-  let+ staking_balance_opt = Storage.Stake.Staking_balance.find ctxt delegate in
-  Option.value staking_balance_opt ~default:Full_staking_balance_repr.zero
-
-let get_initialized_stake ctxt delegate =
-  let open Lwt_result_syntax in
-  let* balance_opt = Storage.Stake.Staking_balance.find ctxt delegate in
-  match balance_opt with
-  | Some staking_balance -> return (staking_balance, ctxt)
-  | None ->
-      let balance = Full_staking_balance_repr.zero in
-      let* ctxt = Storage.Stake.Staking_balance.init ctxt delegate balance in
-      return (balance, ctxt)
+let get_full_staking_balance = Storage.Stake.Staking_balance.get
 
 let has_minimal_stake ctxt
     {Full_staking_balance_repr.own_frozen; staked_frozen; delegated} =
@@ -108,9 +95,25 @@ let has_minimal_stake_and_frozen_stake ctxt
   Tez_repr.(own_frozen >= minimal_frozen_stake)
   && has_minimal_stake ctxt full_staking_balance
 
+let initialize_delegate ctxt delegate ~delegated =
+  let open Lwt_result_syntax in
+  let balance =
+    Full_staking_balance_repr.make
+      ~own_frozen:Tez_repr.zero
+      ~staked_frozen:Tez_repr.zero
+      ~delegated
+  in
+  let* ctxt = Storage.Stake.Staking_balance.init ctxt delegate balance in
+  if has_minimal_stake ctxt balance then
+    let*! ctxt =
+      Storage.Stake.Active_delegates_with_minimal_stake.add ctxt delegate ()
+    in
+    return ctxt
+  else return ctxt
+
 let update_stake ~f ctxt delegate =
   let open Lwt_result_syntax in
-  let* staking_balance_before, ctxt = get_initialized_stake ctxt delegate in
+  let* staking_balance_before = get_full_staking_balance ctxt delegate in
   let*? staking_balance = f staking_balance_before in
   let* ctxt =
     Storage.Stake.Staking_balance.update ctxt delegate staking_balance
@@ -209,7 +212,7 @@ let set_active ctxt delegate =
   let* ctxt, inactive = Delegate_activation_storage.set_active ctxt delegate in
   if not inactive then return ctxt
   else
-    let* staking_balance, ctxt = get_initialized_stake ctxt delegate in
+    let* staking_balance = get_full_staking_balance ctxt delegate in
     if has_minimal_stake ctxt staking_balance then
       let*! ctxt =
         Storage.Stake.Active_delegates_with_minimal_stake.add ctxt delegate ()
diff --git a/src/proto_alpha/lib_protocol/stake_storage.mli b/src/proto_alpha/lib_protocol/stake_storage.mli
index 413ebf3582f2f9dd8d26a37e1b353b87c1d4a451..440aa77b7761be6533bd4fde831a56182f24971d 100644
--- a/src/proto_alpha/lib_protocol/stake_storage.mli
+++ b/src/proto_alpha/lib_protocol/stake_storage.mli
@@ -34,6 +34,12 @@
     - {!Storage.Stake.Total_active_stake}
 *)
 
+val initialize_delegate :
+  Raw_context.t ->
+  Signature.public_key_hash ->
+  delegated:Tez_repr.t ->
+  Raw_context.t tzresult Lwt.t
+
 val get_full_staking_balance :
   Raw_context.t ->
   Signature.public_key_hash ->