diff --git a/contracts/pools/erc20.sol b/contracts/pools/erc20.sol
index ac7fa04..d68b356 100644
--- a/contracts/pools/erc20.sol
+++ b/contracts/pools/erc20.sol
@@ -79,30 +79,33 @@ contract PoolToken is ReentrancyGuard, DSMath, ERC20Pausable {
     }
 
     /**
-  * @dev get pool token rate
-  * @param tokenAmt total token amount
-  */
-  function getCurrentRate(uint tokenAmt) public returns (uint) {
-    return wdiv(totalSupply(), tokenAmt);
-  }
+      * @dev get pool token rate
+      * @param tokenAmt total token amount
+      */
+    function getCurrentRate(uint tokenAmt) public returns (uint) {
+      return wdiv(totalSupply(), tokenAmt);
+    }
 
+    /**
+      * @dev sets exchange rates
+      */
     function setExchangeRate() public isChief {
       uint _previousRate = exchangeRate;
       uint _totalToken = RateInterface(registry.poolLogic(address(this))).getTotalToken();
       _totalToken = sub(_totalToken, insuranceAmt);
       uint _currentRate = getCurrentRate(_totalToken);
-      require(_currentRate != 0, "currentRate-is-0");
-      if (_currentRate > _previousRate) {
-        uint _difTkn = sub(tokenBalance, _totalToken);
-        if (_difTkn < insuranceAmt) {
-          insuranceAmt = sub(insuranceAmt, _difTkn);
+      require(_currentRate != 0, "current-rate-is-zero");
+      if (_currentRate > _previousRate) { // loss => deduct partially/fully from insurance amount
+        uint _loss = sub(tokenBalance, _totalToken);
+        if (_loss <= insuranceAmt) {
+          insuranceAmt = sub(insuranceAmt, _loss);
           _currentRate = _previousRate;
         } else {
-          insuranceAmt = 0;
           tokenBalance = add(_totalToken, insuranceAmt);
+          insuranceAmt = 0;
           _currentRate = getCurrentRate(tokenBalance);
         }
-      } else {
+      } else { // profit => add to insurance amount
         uint insureFeeAmt = wmul(sub(_totalToken, tokenBalance), registry.insureFee(address(this)));
         insuranceAmt = add(insuranceAmt, insureFeeAmt);
         tokenBalance = sub(_totalToken, insureFeeAmt);
diff --git a/contracts/pools/eth.sol b/contracts/pools/eth.sol
index 0101063..3e0bea7 100644
--- a/contracts/pools/eth.sol
+++ b/contracts/pools/eth.sol
@@ -76,30 +76,33 @@ contract PoolToken is ReentrancyGuard, ERC20Pausable, DSMath {
   }
 
   /**
-  * @dev get pool token rate
-  * @param tokenAmt total token amount
-  */
+    * @dev get pool token rate
+    * @param tokenAmt total token amount
+    */
   function getCurrentRate(uint tokenAmt) public returns (uint) {
     return wdiv(totalSupply(), tokenAmt);
   }
 
+  /**
+    * @dev sets exchange rates
+    */
   function setExchangeRate() public isChief {
     uint _previousRate = exchangeRate;
     uint _totalToken = RateInterface(registry.poolLogic(address(this))).getTotalToken();
     _totalToken = sub(_totalToken, insuranceAmt);
     uint _currentRate = getCurrentRate(_totalToken);
     require(_currentRate != 0, "current-rate-is-zero");
-    if (_currentRate > _previousRate) {
-      uint _difTkn = sub(tokenBalance, _totalToken);
-      if (_difTkn < insuranceAmt) {
-        insuranceAmt = sub(insuranceAmt, _difTkn);
+    if (_currentRate > _previousRate) { // loss => deduct partially/fully from insurance amount
+      uint _loss = sub(tokenBalance, _totalToken);
+      if (_loss <= insuranceAmt) {
+        insuranceAmt = sub(insuranceAmt, _loss);
         _currentRate = _previousRate;
       } else {
-        insuranceAmt = 0;
         tokenBalance = add(_totalToken, insuranceAmt);
+        insuranceAmt = 0;
         _currentRate = getCurrentRate(tokenBalance);
       }
-    } else {
+    } else { // profit => add to insurance amount
       uint insureFeeAmt = wmul(sub(_totalToken, tokenBalance), registry.insureFee(address(this)));
       insuranceAmt = add(insuranceAmt, insureFeeAmt);
       tokenBalance = sub(_totalToken, insureFeeAmt);