The Initial Public Offerings IndeX IPOX

The Initial Public Offerings IndeX (IPOX) covers all Austrian initial public offerings in the official market segment for a period of 18 months after their first listing, including newly issued stock of companies whose stock other than the new category has been listed earlier. Initial public offerings in the regulated and unregulated market segments are omitted from consideration. Each initial public offering enters the IPOX with the first price in public trading and not with the offering price in order to prevent the short-run underpricing phenomenon from affecting the index.

To render the ATX and the IPOX comparable to each other, that is, to exclude a systematic deviation of the IPOX from the ATX, the IPOX is constructed isomorphically to the ATX. The indexes have been identically constructed with respect to the index formulae, the adjustment instances, and the adjustment procedures but differ in the composition of the index sample.

In order to study the performance of both the market segment of governmental and the segment of non-governmental IPOs, the IPOX is split into two subindexes, viz. the IPOX(ÖIAG) and the IPOX(NO-ÖIAG). Since mid-December 1992 five (former) ÖIAG companies have gone public on the Vienna Stock Exchange. The composition of the IPOX(ÖIAG) as of May 31, 1994, and as of October 31, 1995, can be found here.

References:

Haefke, C. and Helmenstein, C. (1996): Forecasting Austrian IPOs: An Application of Linear and Neural Network Error-Correction Models, Journal of Forecasting, vol. 15, pp. 237-251.

IPOX: Institute for Advanced Studies, 1996.