Urs Wälchli

Long-Run Performance of Initial Public Offerings: The Evidence for Switzerland

We estimate the underpricing and long-run performance of Swiss initial public offerings (I-POs) from 1983 to 2000. The average market adjusted initial return is 34.97%. To examine the long-run performance of Swiss IPOs, we compute buy-and-hold abnormal returns, skew-ness-adjusted wealth ratios, and cumulative abnormal returns using 120 months of secondary market returns. In contrast to previous findings for the U.S. and Germany, we do not find strong evidence for a distinct IPO effect. We attribute long-run underperformance to the fact that IPO firms tend to be small firms. It virtually vanishes when we use a small capitalization index as a benchmark. In spite of distinct economic implications and statistical properties, our basic results are similar for all performance measures applied.

Electric field measurements in the vicinity of noctilucent clouds and PMSE

We report mesospheric electric field structure in the vicinity of noctilucent clouds (NLC) and polar mesospheric summer echoes (PMSEs) measured on the DECIMALS-B rocket payload launched during the international rocket-radar campaign NLC-91 from Esrange, Sweden on August 10, 1991. Unusually large vertical E- fields, Ez, about 100–300 mV/m on ascent and greater than 1 V/m on descent were detected at 82.5–84.5 km. The region of the large Ez was clearly limited by the NLC layer on the bottom and by the distinctly separated PMSE layer on the top. A narrow negative peak in the Ez height profile observed on ascent in the lower part of the NLC layer was apparently caused by the interaction of the field mill with impacting NLC particles possibly carrying negative charge. If the impact signature is due to single particles, their size is estimated to at least 0.5 µm and their concentration about 10−4 cm−3 locally. Based on the light-scattering properties of NLC such massive particles can only be a minor part of the NLC population.

First height comparison of noctilucent clouds and simultaneous PMSE

On the night of August 9–10, 1991, two rocket payloads were launched into simultaneously occurring noctilucent clouds (NLC) and polar mesospheric summer echoes (PMSE) above Esrange, a third rocket payload was launched into a NLC where a PMSE was detected 5 minutes later above Esrange, in Sweden as part of the NLC-91 campaign. An aim of this experiment was to compare the vertical structures and locations of the NLC and PMSE events. To this end, in situ optical photometers and particle impact sensors were used to measure the altitude and vertical structure of the NLC layer, while the Cornell University portable radar interferometer (CUPRI) was used to probe the PMSE. Although this comparison is complicated by the horizontal separations between the in situ measurements and the radar volume, and low electron densities which reduced the overall radar reflectivity, we conclude that the PMSE layer in the CUPRI radar volume remained above the NLC layer detected by the in situ instruments by 300 to 2000 m throughout the experiment. We interpret this result as supporting the view that PMSE are more likely to result from the presence of aerosols smaller than the ones optically detectable as NLCs.