Do trade deals benefit small companies?

This set me thinking. The BBC reports “European Union countries have approved plans for trade talks with the United States.” So if the UK stays in the EU, UK companies benefit from the trade deal. 

Nancy Pelosi, US Speaker of the House, will soon begin an official visit to the Republic of Ireland. Before she left she stated there would be “no chance whatsoever” of a post-Brexit trade deal between the US and UK if there were any weakening of the Good Friday Agreement.

I know nations can benefit from trade deals, but I can’t bring to mind a small company profiting as a result of inter-governmental negotiations. Please tell me I am wrong.