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Precious metals investment terms A to Z

XAU Index

The Philadelphia Gold and Silver Index (XAU Index) is a market capitalization index of precious metal mining company stocks. As its name suggests it includes both gold and silver mining companies.

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Eric, the Beginner

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The XAU Index is an index of sixteen mining companies, traded on the Philadelphia Stock Exchange (Monday to Friday, from 9.30 a.m. to 4 p.m. Philadelphia Time.) Along with the AMEX Gold BUGS Index (HUI Index), it is one of the two most watched precious metals indices in the world. It is denoted by the symbol XAU and this may cause some confusion, since under the ISO 4217 currency standard this symbol is also used to denote one ounce of gold.

XAU Index Components

XAU Index components

The XAU Index was established in January 1979 and its initial value was 100. It is reviewed every three months, on the third Friday of March, June, September and December, when the Philadelphia Stock Exchange (PHLX) conducts their share update and XAU Index options expire. PHLX can add or remove companies from the index, responding to changes in the gold and silver mining industry to make sure that companies included in it properly represent the whole industry.


XAU and HUI are the most popular indices for the precious metals mining stocks. There are two main differences between them:

• The XAU Index includes both gold and silver stocks, while the HUI Index includes only gold miners
• The HUI Index doesn’t include hedgers and the XAU Index does. To be precise, HUI includes only stocks that don’t hedge their gold production beyond 1.5 years.

As a result, both indices will not move identically at all times, however differences between them should not be major. Significant breakouts or breakdowns in the mining stocks should be confirmed by both XAU and HUI. If a move is seen in only one of them, it should not be viewed as truly significant until the other index confirms it.

XAU Chart

XAU Ratio

The XAU Index is often compared to the price of gold to see if mining stocks are under- or overvalued relative to gold at a given time. Please take a look at the following chart for details:

tops prediction corrections in gold

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