These claims of “diversity is our strength” appear to be done by a psychologist studying the stock market and companies with female board members.

There are so many free variables that it could always be p-hacked to produce whatever results you want.

For example : they choose the relatively obscure S&P1500 - why not the 500? or the 400, 900, 600?

The authors only look at a 15 year window. So basically every tech company (which will have women) would have outperformed.