diff --git a/app/models/issue/prices_missing.rb b/app/models/issue/prices_missing.rb
index 6cb014af..4400458f 100644
--- a/app/models/issue/prices_missing.rb
+++ b/app/models/issue/prices_missing.rb
@@ -16,7 +16,7 @@ class Issue::PricesMissing < Issue
     missing_prices.each do |ticker, dates|
       next unless issuable.owns_ticker?(ticker)
 
-      oldest_date = dates.min
+      oldest_date = dates.min.to_date
       expected_price_count = (oldest_date..Date.current).count
       prices = Security::Price.find_prices(ticker: ticker, start_date: oldest_date)
       stale = false if prices.count < expected_price_count
diff --git a/test/models/issue/prices_missing_test.rb b/test/models/issue/prices_missing_test.rb
new file mode 100644
index 00000000..5c6a5502
--- /dev/null
+++ b/test/models/issue/prices_missing_test.rb
@@ -0,0 +1,61 @@
+require "test_helper"
+
+class Issue::PricesMissingTest < ActiveSupport::TestCase
+  setup do
+    @issue = Issue::PricesMissing.new
+    @account = Account.new(id: "123abc")
+    @issue.issuable = @account
+  end
+
+  test "stale? returns false when no prices are found" do
+    @issue.append_missing_price("AAPL", (Date.current - 5.days).to_s)
+
+    Security::Price.expects(:find_prices).returns([])
+    @account.expects(:owns_ticker?).with("AAPL").returns(true)
+
+    assert_not @issue.stale?
+  end
+
+  test "stale? returns true when all expected prices are found" do
+    start_date = Date.current - 5.days
+    @issue.append_missing_price("AAPL", start_date.to_s)
+
+    expected_prices = (start_date..Date.current).map { |date| { date: date } }
+    Security::Price.expects(:find_prices).returns(expected_prices)
+    @account.expects(:owns_ticker?).with("AAPL").returns(true)
+
+    assert @issue.stale?
+  end
+
+  test "stale? returns false when some prices are missing" do
+    start_date = Date.current - 5.days
+    @issue.append_missing_price("AAPL", start_date.to_s)
+
+    incomplete_prices = (start_date..Date.current - 2.days).map { |date| { date: date } }
+    Security::Price.expects(:find_prices).returns(incomplete_prices)
+    @account.expects(:owns_ticker?).with("AAPL").returns(true)
+
+    assert_not @issue.stale?
+  end
+
+  test "stale? returns true when the account doesn't own the ticker" do
+    @issue.append_missing_price("AAPL", (Date.current - 5.days).to_s)
+
+    @account.expects(:owns_ticker?).with("AAPL").returns(false)
+
+    assert @issue.stale?
+  end
+
+  test "stale? handles multiple tickers correctly" do
+    @issue.append_missing_price("AAPL", (Date.current - 5.days).to_s)
+    @issue.append_missing_price("GOOGL", (Date.current - 3.days).to_s)
+
+    @account.expects(:owns_ticker?).with("AAPL").returns(true)
+    @account.expects(:owns_ticker?).with("GOOGL").returns(true)
+
+    Security::Price.expects(:find_prices).with(ticker: "AAPL", start_date: Date.current - 5.days).returns([])
+    Security::Price.expects(:find_prices).with(ticker: "GOOGL", start_date: Date.current - 3.days).returns([])
+
+    assert_not @issue.stale?
+  end
+end