Is there ? <a href=" http://headtrash.co.uk/zyprexa-effects.pdf#subjected ">zyprexa effects</a> Why would Dorsey, who has been chairman of Twitter since October 2008, give Williams control of his stake in the company? The filing doesn&#8217;t explain, but new details suggest Dorsey didn&#8217;t have much choice after he lost a power struggle with Williams and Twitter&#8217;s board of directors.