diff --git a/src/commonTest/kotlin/exchange.dydx.abacus/payload/v4/V4MarketsTests.kt b/src/commonTest/kotlin/exchange.dydx.abacus/payload/v4/V4MarketsTests.kt
index b358c7b9b..ab9a36b81 100644
--- a/src/commonTest/kotlin/exchange.dydx.abacus/payload/v4/V4MarketsTests.kt
+++ b/src/commonTest/kotlin/exchange.dydx.abacus/payload/v4/V4MarketsTests.kt
@@ -73,6 +73,9 @@ class V4MarketsTests : V4BaseTests() {
 
         testTradesBatchChanged()
         time = perp.log("Trades Batch Changed", time)
+
+        testEffectiveIMF()
+        time = perp.log("Calculate Effective IMF", time)
     }
 
     private fun testMarketsSubscribed() {
@@ -637,4 +640,119 @@ class V4MarketsTests : V4BaseTests() {
             },
         )
     }
+
+    fun testEffectiveIMF() {
+        test(
+            {
+                perp.socket(
+                    testWsUrl,
+                    mock.marketsChannel.v4_subscribed_for_effective_imf_calculation,
+                    0,
+                    null,
+                )
+            },
+            """
+            {
+               "markets":{
+                  "markets":{
+                     "BTC-USD":{
+                        "priceChange24H":0.0,
+                        "market":"BTC-USD",
+                        "oraclePrice":0,
+                        "status":{
+                           "canTrade":true,
+                           "canReduce":true
+                        },
+                        "configs":{
+                           "maintenanceMarginFraction":0.03,
+                           "incrementalInitialMarginFraction":0.0,
+                           "incrementalPositionSize":0.0,
+                           "initialMarginFraction":0.05,
+                           "clobPairId":0,
+                           "baselinePositionSize":0.0,
+                           "effectiveInitialMarginFraction": 0.05
+                        },
+                        "perpetual":{
+                           "volume24H":4.936082546194518E8,
+                           "openInterest":3530.502834378,
+                           "nextFundingRate":0.0,
+                           "trades24H":922707
+                        }
+                     },
+                     "ETH-USD":{
+                        "priceChange24H":0.0,
+                        "market":"ETH-USD",
+                        "oraclePrice":1000.0,
+                        "status":{
+                           "canTrade":true,
+                           "canReduce":true
+                        },
+                        "configs":{
+                           "maintenanceMarginFraction":0.03,
+                           "incrementalInitialMarginFraction":0.0,
+                           "incrementalPositionSize":0.0,
+                           "initialMarginFraction":0.01,
+                           "clobPairId":1,
+                           "baselinePositionSize":0.0,
+                           "effectiveInitialMarginFraction": 0.6
+                        },
+                        "perpetual":{
+                           "volume24H":4.931478367879293E8,
+                           "openInterest":1000,
+                           "nextFundingRate":0.0,
+                           "trades24H":939311
+                        }
+                     },
+                     "MATIC-USD":{
+                        "priceChange24H":0.1,
+                        "market":"MATIC-USD",
+                        "oraclePrice":57.80445,
+                        "status":{
+                           "canTrade":true,
+                           "canReduce":true
+                        },
+                        "configs":{
+                           "maintenanceMarginFraction":0.03,
+                           "incrementalPositionSize":0.0,
+                           "initialMarginFraction":0.02,
+                           "clobPairId":33,
+                           "baselinePositionSize":0.0,
+                           "effectiveInitialMarginFraction": 1.0
+                        },
+                        "perpetual":{
+                           "volume24H":0,
+                           "openInterest":5231.255,
+                           "nextFundingRate":0.0,
+                           "trades24H":0
+                        }
+                     },
+                     "ENJ-USD":{
+                        "priceChange24H":0.0,
+                        "market":"ENJ-USD",
+                        "oraclePrice":0.4472,
+                        "status":{
+                           "canTrade":true,
+                           "canReduce":true
+                        },
+                        "configs":{
+                           "maintenanceMarginFraction":0.03,
+                           "incrementalPositionSize":0.0,
+                           "initialMarginFraction":0.05,
+                           "clobPairId":59,
+                           "baselinePositionSize":0.0,
+                           "effectiveInitialMarginFraction": .05
+                        },
+                        "perpetual":{
+                           "volume24H":0,
+                           "openInterest":1200.24,
+                           "nextFundingRate":0.0,
+                           "trades24H":0
+                        }
+                     }
+                  }
+               }
+            }
+            """.trimIndent(),
+        )
+    }
 }
diff --git a/src/commonTest/kotlin/exchange.dydx.abacus/tests/payloads/MarketsChannelMock.kt b/src/commonTest/kotlin/exchange.dydx.abacus/tests/payloads/MarketsChannelMock.kt
index e207d0b59..3da95d50e 100644
--- a/src/commonTest/kotlin/exchange.dydx.abacus/tests/payloads/MarketsChannelMock.kt
+++ b/src/commonTest/kotlin/exchange.dydx.abacus/tests/payloads/MarketsChannelMock.kt
@@ -1225,6 +1225,139 @@ internal class MarketsChannelMock {
         }
     """.trimIndent()
 
+      /*
+        Cases this mock tests:
+        - First pair (BTC-USD) is missing upper and lower cap. effectiveIMF should default to regular IMF
+        - Second pair (ETH-USD) lowerCap < openInterest x oraclePrice < upperCap. effectiveIMF should
+          be a number between baseIMF and 1.0
+        - Third pair (MATIC-USD) openInterest x oracePrice > upperCap. effective IMF should be 1
+        - Fourth pair (ENJ-USD) openInterest < lowerCap. effective IMF should equal regular IMF
+       */
+    internal val v4_subscribed_for_effective_imf_calculation = """
+    {
+       "type":"subscribed",
+       "connection_id":"d8caff8c-0ee8-4eb0-b124-20c2d3d956ba",
+       "message_id":1,
+       "channel":"v4_markets",
+       "contents":{
+          "markets":{
+             "BTC-USD":{
+                "clobPairId":"0",
+                "ticker":"BTC-USD",
+                "status":"ACTIVE",
+                "lastPrice":"0",
+                "oraclePrice":"0",
+                "priceChange24H":"0",
+                "volume24H":"493608254.61945181460",
+                "trades24H":922707,
+                "nextFundingRate":"0",
+                "nextFundingUpdate":0,
+                "initialMarginFraction":"0.0523",
+                "incrementalInitialMarginFraction":"0",
+                "maintenanceMarginFraction":"0.030000",
+                "basePositionSize":"0",
+                "incrementalPositionSize":"0",
+                "maxPositionSize":"0",
+                "stepBaseQuantums":1000000,
+                "subticksPerTick":10000,
+                "openInterest":"3530.502834378",
+                "atomicResolution":-10,
+                "quantumConversionExponent":-8,
+                "tickSize":"0.01",
+                "stepSize":"0.000000001",
+                "stepBaseQuantums":10
+             },
+             "ETH-USD":{
+                "clobPairId":"1",
+                "ticker":"ETH-USD",
+                "status":"ACTIVE",
+                "lastPrice":"0",
+                "oraclePrice":"1000",
+                "priceChange24H":"0",
+                "volume24H":"493147836.787929310",
+                "trades24H":939311,
+                "nextFundingRate":"0",
+                "nextFundingUpdate":0,
+                "initialMarginFraction":"0.01",
+                "incrementalInitialMarginFraction":"0",
+                "maintenanceMarginFraction":"0.030000",
+                "basePositionSize":"0",
+                "incrementalPositionSize":"0",
+                "maxPositionSize":"0",
+                "stepBaseQuantums":1000000,
+                "subticksPerTick":10000,
+                "openInterest":"1000",
+                "openInterestLowerCap": "100000",
+                "openInterestUpperCap": "1500000",
+                "atomicResolution":-9,
+                "quantumConversionExponent":-9,
+                "tickSize":"0.001",
+                "stepSize":"0.001",
+                "stepBaseQuantums":1000
+             },
+             "MATIC-USD":{
+               "clobPairId":"33",
+               "ticker":"MATIC-USD",
+               "status":"ACTIVE",
+               "lastPrice":"0",
+               "oraclePrice":"57.80445",
+               "priceChange24H":"0.1",
+               "volume24H":"0",
+               "trades24H":0,
+               "nextFundingRate":"0",
+               "initialMarginFraction":"0.02",
+               "maintenanceMarginFraction":"0.03",
+               "basePositionSize":"0",
+               "openInterest":"5231.255",
+               "openInterestLowerCap": "83",
+               "openInterestUpperCap": "5500",
+               "incrementalPositionSize":"0",
+               "atomicResolution":-10,
+               "quantumConversionExponent":-8,
+               "tickSize":"100000",
+               "stepSize":"0.0001",
+               "stepBaseQuantums":1000000,
+               "subticksPerTick":1000000000,
+               "atomicResolution":-9,
+               "quantumConversionExponent":-9,
+               "tickSize":"0.001",
+               "stepSize":"0.001",
+               "stepBaseQuantums":1000
+            },
+             "ENJ-USD": {
+               "clobPairId":"59",
+               "ticker":"ENJ-USD",
+               "status":"ACTIVE",
+               "lastPrice":"0",
+               "oraclePrice":".4472",
+               "priceChange24H":"0",
+               "volume24H":"0",
+               "trades24H":0,
+               "nextFundingRate":"0",
+               "initialMarginFraction":"0.05",
+               "maintenanceMarginFraction":"0.03",
+               "basePositionSize":"0",
+               "openInterest":"1200.24",
+               "openInterestLowerCap": "1000",
+               "openInterestUpperCap": "15000",
+               "incrementalPositionSize":"0",
+               "atomicResolution":-10,
+               "quantumConversionExponent":-8,
+               "tickSize":"100000",
+               "stepSize":"0.0001",
+               "stepBaseQuantums":1000000,
+               "subticksPerTick":1000000000,
+               "atomicResolution":-9,
+               "quantumConversionExponent":-9,
+               "tickSize":"0.001",
+               "stepSize":"0.001",
+               "stepBaseQuantums":1000
+             }
+          }
+       }
+    }
+    """.trimIndent()
+
     internal val v4_channel_data = """
         {
            "type":"channel_data",