Austrian Traded Index

When the Austrian Futures and Options Exchange (ÖTOB) was established in 1991, the ATX was constituted to fulfill both descriptive and operative functions of a representative stock market index. Since November 1995, the ATX is the core of a family of stock market indexes that comprises the ATX, the ATX 50, the ATX 50 Performance (ATX 50P), and the ATX MidCap.

As an aggregate market indicator the ATX, documents the price dynamics of the 22 most liquid market segments of Austrian stocks which represent about 87.5% of total stock market turnover and about 69.6% of total market capitalization at the beginning of 1998. Simultaneously, it also serves as an underlying for futures and options contracts.

Regarding its construction principle, the ATX and the other members of the index family belong to the category of capitalization-weighted value ratios with daily chaining. Note that the market capitalization is corrected by a free float factor, which is intended to ensure that the weight of a particular title in the ATX corresponds to the amount of capital actually available for public trading on the stock exchange. The selection of the index sample is carried out according to the following three criteria: 

  • liquidity
  • all stocks that are included in the index must be listed in the official market segment of continuously traded stocks
  • market capitalization 
  • eligible stocks must belong to the stocks with the largest market capitalization on the Vienna Stock Exchange
  • free floating capital. 
A sufficiently large free floating capital is required for a stock to be included in the ATX. The number of outstanding shares taken into account for calculating the weight of each stock in the index is lowered by a flat rate of 50% if the free floating capital is less than 25% of the total outstanding capital of the respective stock. 

Since the ATX is intended to reflect all price changes caused by market fluctuations, the index is adjusted as totechnical price changes except for those due to dividend payments. If a stock is suspended from trading, the last available price is used for calculating the index.

Austrian Traded Index, ATX: Vienna Stock Exchange, Vienna. Text: Institute for Advanced Studies, Vienna, 1998. All rights reserved.

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