From 9e30f9a2a95c2d42c2e039e0938fbe94317b4af3 Mon Sep 17 00:00:00 2001
From: Chrstopher Hunter <8398225+crhntr@users.noreply.github.com>
Date: Mon, 2 Sep 2024 22:31:20 -0700
Subject: [PATCH] use negative zscore to flip the sign on VaR

---
 calculate/stats.go      | 2 +-
 calculate/stats_test.go | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/calculate/stats.go b/calculate/stats.go
index d80ce88..5265e59 100644
--- a/calculate/stats.go
+++ b/calculate/stats.go
@@ -73,7 +73,7 @@ func ValueAtRisk(values []float64, portfolioValue, confidenceLevel, periodsPerYe
 		Sigma: 1.0,
 	}
 	zScore := normal.Quantile(confidenceLevel)
-	return portfolioValue * zScore * AnnualizeRisk(stat.PopStdDev(values, nil), periodsPerYear)
+	return portfolioValue * -zScore * AnnualizeRisk(stat.PopStdDev(values, nil), periodsPerYear)
 }
 
 func negativeValues(out, in []float64) []float64 {
diff --git a/calculate/stats_test.go b/calculate/stats_test.go
index 6b8fc7c..7d1a8a3 100644
--- a/calculate/stats_test.go
+++ b/calculate/stats_test.go
@@ -86,7 +86,7 @@ func TestMetrics(t *testing.T) {
 			confidenceLevel = 0.95
 		)
 		result := ValueAtRisk(portfolio, portfolioValue, confidenceLevel, PeriodsPerYear)
-		assert.InDelta(t, 2148.94, result, 0.01)
+		assert.InDelta(t, -2148.94, result, 0.01)
 	})
 }