diff --git a/app/Console/Commands/FixCostBasisForSales.php b/app/Console/Commands/FixCostBasisForSales.php
new file mode 100644
index 0000000..2e9544c
--- /dev/null
+++ b/app/Console/Commands/FixCostBasisForSales.php
@@ -0,0 +1,73 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Console\Commands;
+
+use App\Models\Transaction;
+use Illuminate\Console\Command;
+
+class FixCostBasisForSales extends Command
+{
+    /**
+     * The name and signature of the console command.
+     *
+     * @var string
+     */
+    protected $signature = 'fix:cost-basis-for-sales
+                                    {portfolio_id : The ID of the portfolio to fix.}';
+
+    /**
+     * The console command description.
+     *
+     * @var string
+     */
+    protected $description = 'Fixes broken costs basis for sale transactions';
+
+    /**
+     * Create a new command instance.
+     *
+     * @return void
+     */
+    public function __construct()
+    {
+        parent::__construct();
+    }
+
+    /**
+     * Execute the console command.
+     *
+     * @return int
+     */
+    public function handle()
+    {
+
+        $transactions = Transaction::where(['transaction_type' => 'SELL', 'portfolio_id' => $this->argument('portfolio_id')])->get();
+
+        $transactions->chunk(10)->each(function ($chunk) {
+
+            dispatch(function () use ($chunk) {
+
+                $chunk->each(function ($transaction) {
+
+                    $cost_basis = Transaction::where([
+                        'portfolio_id' => $transaction->portfolio_id,
+                        'symbol' => $transaction->symbol,
+                        'transaction_type' => 'BUY',
+                    ])->whereDate('date', '<=', $transaction->date)
+                        ->selectRaw('SUM(transactions.cost_basis * transactions.quantity) as total_cost_basis')
+                        ->selectRaw('SUM(transactions.quantity) as total_quantity')
+                        ->first();
+
+                    $average_cost_basis = empty($cost_basis->total_quantity)
+                        ? 0
+                        : $cost_basis->total_cost_basis / $cost_basis->total_quantity;
+
+                    $transaction->cost_basis = $average_cost_basis ?? 0;
+
+                    $transaction->save();
+                });
+            });
+        });
+    }
+}