It would need to be stronger than EU member states' influence, which seems unlikely. I also don't remember ever hearing of even attempts to exert influence on these investigations.

Note that such agency actions are firewalled from even their EU/US/national political leadership. Even if Trump managed to convince Merkel to intervene, she wouldn't really be able to. To illustrate with a reverse example: Imagine Macron trying to get to get to a judge in a California District Court. There are multiple layers in between where they would tend to consider the call a prank and hang up.

And maybe more capital is directed towards lawyers and litigation making it more expensive and difficult to extract cash from large US companies.