A proposed class action by investors has targeted Charles Schwab & Co. alleging the discount brokerage failed in its duties to perform best execution in client trades. In early March, the same investors filed a complaint seeking to compel UBS to produce documents about the trades, which are the subject of their dispute with Schwab.

The two-pronged legal strategy seems likely to lead investors to make related claims against UBS, lawyers believe.

The investors have filed complaints in federal courts in San Francisco and Manhattan, both of which focus on trades executed by Schwab between 2011 and 2014.

According to the complaint filed in San Francisco, Schwab omitted material facts about its duty of best execution and failed to disclose a handling agreement that permitted UBS to direct retail orders to dark pools – private exchanges not accessible to the investing public.

The complaint alleges:

“Schwab’s clients’ orders were unsophisticated, and UBS made them available to [high frequency trading platforms] HFTs. HFTs executed many thousands of times the number of trades that an average retail investor made by utilizing computer algorithms to rapidly trade securities. These programs allowed the HFTs to opportunistically move in and out of positions in seconds, profiting by fractions of a cent, hundreds of thousands of times a day. As a result, the HFTs, and UBS, profited from Schwab’s customers because they could exploit that order flow to obtain better prices on the same securities and monitor the marketplace.”

In the Manhattan federal court, the investors filed a complaint in early March asking the court to order UBS to produce documents related to the trades.

“Potentially, the greatest harm coming from this dispute to UBS or Schwab will be the bad publicity if it is determined that either benefited from trades in a way that wasn’t beneficial to investors,” says Thomas Lewis, an attorney at Lawrenceville, N.J.-based firm Stevens & Lee, who represents both financial advisors and their employers but none of the parties in this litigation.

It is likely the Manhattan court will order UBS to produce the documents and that the investors will then add UBS as defendant in the San Francisco case, Lewis says.

“There is a better chance than not that UBS will be named,” he says.

For UBS advisors, however, the real risk will only come with the publicity, Lewis predicts.

“Their biggest problem is the court of public perception. I think this will be a nonevent for the advisors except when the articles get out and clients start asking questions,” Lewis says.

A UBS spokesperson declined to comment on the pending litigation.

In an emailed response, a Schwab spokesperson said: “We are committed to providing clients with best execution and have a strong track record of meeting those obligations. Execution quality always takes priority when determining where to route orders. We will continue to vigorously defend against plaintiffs’ claims, which are entirely without merit.”