diff --git a/src/my_project/interviews/top_150_questions_round_18/best_time_to_sell.py b/src/my_project/interviews/top_150_questions_round_18/best_time_to_sell.py
new file mode 100644
index 00000000..ba474c43
--- /dev/null
+++ b/src/my_project/interviews/top_150_questions_round_18/best_time_to_sell.py
@@ -0,0 +1,18 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+import math 
+
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+
+        min_price = math.inf
+        max_profit = 0
+        len_prices = len(prices)
+
+        for i in range(len_prices):
+            if prices[i] < min_price:
+                min_price = prices[i]
+            elif prices[i] - min_price > max_profit:
+                max_profit = prices[i] - min_price
+
+        return max_profit
\ No newline at end of file
diff --git a/tests/test_150_questions_round_18/test_best_time_to_sell_round_18.py b/tests/test_150_questions_round_18/test_best_time_to_sell_round_18.py
new file mode 100644
index 00000000..798de5b1
--- /dev/null
+++ b/tests/test_150_questions_round_18/test_best_time_to_sell_round_18.py
@@ -0,0 +1,11 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_18\
+.best_time_to_sell import Solution
+
+class BestTimeToSellStockTestCase(unittest.TestCase):
+
+    def test_best_time_to_sell_stock(self):
+        solution = Solution()
+        output = solution.maxProfit(prices=[7,1,5,3,6,4])
+        target = 5 
+        self.assertEqual(output, target)