What's The Difference Between Adjusted Close Price and Close Price?

The Close Price and Adjusted Close Price represent the price of a stock at the end of a trading day, but they differ in how they account for corporate actions that can affect a stock's price.

Here's a breakdown:

• Close Price: This is simply the final price at which a stock traded during regular trading hours on a given day. It's the raw, unadjusted price.

• Adjusted Close Price: This price takes into account corporate actions like:

  • Dividends: Cash payments made to shareholders.

  • Stock Splits: When a company increases the number of its shares outstanding by dividing each existing share into multiple shares.

  • Stock Dividends: Distributing additional shares to existing shareholders instead of cash.

  • Rights Issues/Offerings: Giving existing shareholders the right to purchase additional shares at a discount.

  • Spin-offs: Creating a new independent company by distributing shares of that business to existing shareholders.

How the Adjustment Works:

The adjusted close price adjusts previous closing prices to reflect the effect of these corporate actions. The goal is to provide a more accurate view of a stock's historical performance, especially over long periods.

Example:

Let's say a stock closes at $100. Then, the company issues a 2-for-1 stock split (each share becomes two). Immediately after the split, the stock price should roughly halve to around $50 (ignoring market forces).

• The Close Price on the day of the split would be the actual price at which the stock closes after the split (around $50).

• The Adjusted Close Price for all dates before the split would be recalculated, effectively dividing the historical closing prices by 2. So, the previous day's close of $100 would be adjusted down to $50. This ensures that when you chart the adjusted close price, you get a continuous line that accounts for the split, rather than a sudden 50% drop that is simply due to the increased number of shares.

Why Use Adjusted Close Price?

• Accurate Historical Returns: The adjusted close price is crucial for calculating accurate historical returns. If you use the unadjusted close price, the stock split (or dividend, etc.) would look like a huge price drop, even though it's just a change in the number of shares. Using adjusted close avoids this.

• Long-Term Trend Analysis: For long-term analysis and charting, the adjusted close price provides a more reliable picture of how a stock has performed over time.

• Backtesting: When backtesting trading strategies, you must use adjusted close prices. Using unadjusted prices will lead to inaccurate and potentially disastrous results because your backtest will be falsely penalizing your strategy for corporate actions.

When is Close Price Useful?

The Close Price is most useful for:

• Short-term trading: For very short-term trading decisions (e.g., day trading), the immediate close price is most relevant.

• Real-time analysis: If you're looking at the current day's price action, the real-time or end-of-day close price is what matters.

In summary:

Feature	Close Price	Adjusted Close Price
Definition	Final price of the day	Final price adjusted for corporate actions
Usefulness	Short-term trading, real-time	Long-term analysis, historical returns, backtesting
Impact of Splits	Shows a gap in price	Accounts for the split, provides a continuous line

For almost all analyses involving time series of stock prices covering significant periods, you should use the adjusted close price. Using unadjusted prices for these purposes can be highly misleading.