Yes, it can be traced back to you exactly the way you decribe: someone finds out that InvestCo is 50% owned by HoldingLLC; then they investigage HoldingLLC and find the ownership. This requires a bit of detective work, but unless one of the companies is established in a jurisdiction where ownership is not listed or reported and which is not subject to U.S. legal process, someone who is determined enough can trace back to you. This is a reason why some companies are set up in jurisdications like the Cayman Islands.