Nikkei 225 Stock Average

Rows: 20,098
Columns: 2

Daily closing prices for the Nikkei 225, the primary stock market index for Japan.

AI analysis

Nikkei 225 Dataset Analysis

Dataset Overview & Value for Correlation Studies This dataset captures the full historical daily closing prices of the Nikkei 225, Japan's premier equity benchmark tracking 225 blue-chip companies listed on the Tokyo Stock Exchange. Sourced from the Federal Reserve Bank of St. Louis's FRED API (https://fred.stlouisfed.org), this is a highly credible, institutionally maintained series — FRED is known for regular updates and long historical coverage, suggesting this data likely spans several decades of market history. With 20,098 daily observations, this series is exceptionally well-suited for long-horizon financial correlation studies, including comparisons against macroeconomic indicators, currency pairs, commodity prices, and other global equity indices.

Data Quality Observations The dataset is structurally lean with just 2 columns, and the Date column is pristine — zero nulls across all 20,098 rows with perfect distinct cardinality, confirming it functions reliably as a unique identifier. The primary concern is the NIKKEI225 price column, which carries 974 null values (4.8% of rows). This is the dataset's only quality issue but a meaningful one. These missing values likely correspond to Japanese market holidays, weekends, or periods where FRED did not record a value — a common pattern in financial time series sourced from APIs that log calendar days rather than trading days only. Duplicate row counts are pending Phase D recomputation, but given the perfect distinctness of the Date column, true duplicates are unlikely. Downstream analyses should apply forward-fill or explicit holiday masking before modeling.

Key Column Distributions The NIKKEI225 column tells a rich story through its statistics. The mean of 11,769 sits notably above the median of 9,701, immediately signaling rightward skew (confirmed at skew = 1.07), driven by the index's dramatic rise toward its recent highs. The interquartile range is extraordinarily wide — Q1 at 1,674 vs. Q3 at 18,310 — reflecting the index's journey from post-war lows through the 1980s bubble peak and subsequent recovery cycles. The minimum of 85.25 points to very early historical records (likely 1950s), while the maximum of 65,158 reflects the 2024 all-time high. The 176 flagged outliers and a standard deviation of 10,667 (nearly equal to the mean) underscore just how non-stationary this series is — standard correlation on raw price levels is inadvisable; log returns or differencing are essential preprocessing steps.

Recommended Join Key The Date column is the clear and unambiguous join key — it has zero nulls and 20,098 distinct values, making it a perfect 1:1 anchor for cross-dataset merges. When joining to datasets that use trading-day calendars (e.g., US equity indices), analysts should be mindful that Japanese and US market holidays differ, and an inner join will naturally exclude non-overlapping dates. For macro datasets with monthly or quarterly granularity, the Date column should be aggregated (e.g., month-end close or period average) prior to joining.

Suggested Correlation Datasets Several dataset categories would pair powerfully with this series. USD/JPY exchange rate data (also available via FRED) is a natural first pairing, given the well-documented relationship between yen strength and Nikkei performance, especially for export-heavy constituents. S&P 500 and FTSE 100 daily closing prices would enable global equity co-movement and contagion studies. Japan GDP, inflation (CPI), and Bank of Japan interest rate decisions would support macroeconomic regime analysis. Crude oil prices (WTI or Brent) are relevant given Japan's energy import dependency and its effect on corporate margins. Finally, VIX (CBOE Volatility Index) data would enable risk-appetite correlation studies, particularly around crisis periods like 2008, 2011 (Fukushima), and 2020 (COVID-19), all of which should be visibly encoded as structural breaks in this series.

Columns

Date (date)
NIKKEI225 (decimal)