Why wouldn't you believe it? Racism against white men has been commonplace in US corporations for decades.
Do you disagree?
Any claim that racism against white men is common has to reconcile this fact. If the system is so biased against them, how do they end up so incredibly overrepresented? Are they so much better than everyone else that they get most of the spots despite this unjust discrimination? Or maybe the bias actually goes the other way.
And do you think upper management was more or less than 90% white?