valueandopportunity

In my last post about potential short candidates, I said:

Personally, I would hesitate to short anything above a 15%-20% percentage of SI/Free float although I have no “hard knowledge” to support this.

In the comments, Winter correctly pointed out that one could also argue the other way around, the higher the short interest, the higher the possibility that the stock will drop.

Interestingly, for many trades, stocks with high short interests seem to be attractive long opportunities as pages like this show.

To quote them:

Stocks with high short interest are often very volatile and are well known for making explosive upside moves (known as a short squeeze). Stock traders will often flock to such stocks for no reason other than the fact that they have a high short interest and the price can potentially move up very quickly as traders with open short positions move to cover.

Googling around a littel bit I found the following interesting paper called Short Interest and Stock Returns

The introduction starts of supporting Winter comment:

It is now widely accepted that stocks with high short interest ratios underperform the market. This is a very recent bit of conventional wisdom, based largely on the evidence in Asquith and Meulbroek’s (1995) unpublished working paper for New York Stock Exchange (NYSE) and American Stock Exchange (Amex) stocks, and Desai, Ramesh, Thiagarajan, and Balachandran’s (2002) article for Nasdaq stocks. Both Asquith and Meulbroek and Desai et al report negative and significant abnormal returns for firms with short interest ratios of 2.5% or more, where the short interest ratio is defined as the ratio of short interest to shares outstanding. Both papers also report large secular increases in short interest ratios, and skewed cross-sectional distributions, with most stocks having short interest ratios of less than 0.5%, and very few firms having a ratio exceeding 10%. Prior to these papers, the conventional wisdom was that large short positions presaged positive future returns, caused by the flow demand from short sellers covering their positions

The paper is worth a read. In general, the authors confirm that stocks with high short ratios seem to underperform:

Consistent with other studies, we find that the higher the short interest ratio, the lower is the subsequent performance. That is, firms with short interest ratios of 10% or more underperform those of 5% or 2.5%.

Their research shows that the effect is not so significant as previously thought and that it only works for equal weighted portfolios, not for market cap weighted portfolios.

They paper also gives a good overview of ohter papers on this topic, it seems to be that this area is not as well researched as others.

Their results can be summarized with this quote:

We find that the underperformance of high short interest firms is fairly brief, and only rapid portfolio turnover allows us to realize this underperformance. We also examine whether high short interest is based only on valuation concerns and find that convertible bond arbitrage is a major reason for high short interest as well. Finally, we show that the performance of high short interest NYSE-Amex stocks is more severe and consistent than for their Nasdaq 24 counterparts over the period July 1988-2002, and that small cap firms make up a large portion of the firms that are highly shorted.

Howver they question if a such a strategy can be effectively implemented especially as the overall universe of high short interest stocks is relatively small.

One aspect is missing in the paper in my opnbion : As far as I could see they did not explicitly incorporate volatility of returns. So the outperformance could be just the effect of a much higher volatility of those shares.

However as a first summary, I will have to rethink my gut feeling to stay away from stocks with high short interest.

It might make also sense for short idea generation to use those short interest tables, especially AMEX/ NYSE stocks.

Currently the NYSE page from the link mentioned above shows the following top 20 NYSE stocks with high short interest:

Some of those stocks even show up regulary on value blogs. So another application of such lists could be to even more scrutinize “value stocks” with high short interest as they might be potential value traps.

A final word on European stocks: Unfortunately, the disclosure of short interest in Europe is close to non-existent. Also, as the Volkswagen example showed, “cornering” is still an issue with European stocks. So in any case one should be extra carefull with single stock shorts.