diff --git a/core/execution/amm/engine.go b/core/execution/amm/engine.go
index a97008aa14..5dbc803828 100644
--- a/core/execution/amm/engine.go
+++ b/core/execution/amm/engine.go
@@ -474,7 +474,9 @@ func (e *Engine) submit(active []*Pool, agg *types.Order, inner, outer *num.Uint
 }
 
 // partition takes the given price range and returns which pools have volume in that region, and
-// divides that range into sub-levels where AMM boundaries end.
+// divides that range into sub-levels where AMM boundaries end. Note that `outer` can be nil for the case
+// where the incoming order is a market order (so we have no bound on the price), and we've already consumed
+// all volume on the orderbook.
 func (e *Engine) partition(agg *types.Order, inner, outer *num.Uint) ([]*Pool, []*num.Uint) {
 	active := []*Pool{}
 	bounds := map[string]*num.Uint{}
@@ -503,7 +505,7 @@ func (e *Engine) partition(agg *types.Order, inner, outer *num.Uint) ([]*Pool, [
 	// This is because to get the BUY volume an AMM has at price P, we need to calculate the difference
 	// in its position between prices P -> P + 1. For SELL volume its the other way around and we
 	// need the difference in position from P - 1 -> P.
-	if inner.EQ(outer) {
+	if inner != nil && outer != nil && inner.EQ(outer) {
 		if agg.Side == types.SideSell {
 			outer = num.UintZero().Add(outer, e.oneTick)
 		} else {
diff --git a/core/execution/amm/engine_test.go b/core/execution/amm/engine_test.go
index 6f616d8569..77c0dd7b42 100644
--- a/core/execution/amm/engine_test.go
+++ b/core/execution/amm/engine_test.go
@@ -51,6 +51,7 @@ func TestAMMTrading(t *testing.T) {
 	t.Run("test basic submit order", testBasicSubmitOrder)
 	t.Run("test submit order at best price", testSubmitOrderAtBestPrice)
 	t.Run("test submit market order", testSubmitMarketOrder)
+	t.Run("test submit market order unbounded", testSubmitMarketOrderUnbounded)
 	t.Run("test submit order pro rata", testSubmitOrderProRata)
 	t.Run("test best prices and volume", testBestPricesAndVolume)
 
@@ -269,6 +270,31 @@ func testSubmitMarketOrder(t *testing.T) {
 	assert.Equal(t, 126420, int(orders[0].Size))
 }
 
+func testSubmitMarketOrderUnbounded(t *testing.T) {
+	tst := getTestEngine(t)
+
+	party, subAccount := getParty(t, tst)
+	submit := getPoolSubmission(t, party, tst.marketID)
+
+	expectSubaccountCreation(t, tst, party, subAccount)
+	whenAMMIsSubmitted(t, tst, submit)
+
+	// now submit an order against it
+	agg := &types.Order{
+		Size:      1000000,
+		Remaining: 1000000,
+		Side:      types.SideSell,
+		Price:     num.NewUint(0),
+		Type:      types.OrderTypeMarket,
+	}
+
+	ensurePosition(t, tst.pos, 0, num.NewUint(0))
+	orders := tst.engine.SubmitOrder(agg, num.NewUint(1980), nil)
+	require.Len(t, orders, 1)
+	assert.Equal(t, "1960", orders[0].Price.String())
+	assert.Equal(t, 1000000, int(orders[0].Size))
+}
+
 func testSubmitOrderProRata(t *testing.T) {
 	tst := getTestEngine(t)