It is found that partial correlations between 12 major US equity sector ETFs conditioned on the state of economy (mimicked here by the S&P 500 index) are significantly lower than the Pearson's correlations. The Markowitz mean-variance portfolio theory is modified in terms of partial covariance....

We compared performance of past ‘winners' and past ‘losers' over the look-ahead period of one month for various portfolios that consist of the US ETFs and the holdings of the US equity Select Sector SPDRs in 2007 – 2017 and 2011 - 2017. Namely, we verified the conventional pattern...

Using web search data obtained with Google Trends, we found that some companies among the S&P 500 constituents have persistently high search scores. Many of these companies provide consumer products/services. Mean-variance optimal portfolios composed of these companies have significantly...