Refer to the input text as context and select the correct relationship between 'Sergio Marchionne' and 'Fiat' from the available options.
Options: position held, industry, employer, subsidiary

UAW President Dennis Williams is seeking ratification of the tentative agreement he reached with Fiat Chrysler Chief Executive Officer Sergio Marchionne so he can move on to Ford Motor Co. and General Motors Co. to seek similar, but more lucrative deals.
employer