Turning up the heat in its battle to acquire electronic materials manufacturer Versum, Germany’s Merck KGaA has filed a preliminary proxy statement with the US Securities and Exchange Commission (SEC), urging all Versum shareholders to vote against the $3.8 billion all-stock merger with Entegris and related proposals at the US company’s special meeting of shareholders to bless the plans.

Merck said it is convinced that the proposed merger is not the best option available to Versum shareholders and that its own all-cash proposal – valued at $48 per share, or $5.9 billion in total – is superior.

A vote against the Entegris transaction would send a “clear message” to Versum’s board that a transaction for a lower premium than that reflected in Merck’s proposal “is not the desired outcome,” the Darmstadt-based group added. Accordingly, it said the board of the 2016 spin-off of Air Products & Chemicals should engage with it in good faith to share confidential data, negotiate and determine that it is prepared to execute a definitive agreement.

Merck said its push for Versum is in line with the stockholder rights plan (poison pill) the company issued on Feb. 28, the day before Versum’s board officially rejected the German offer. This would give all stockholders the right to purchase more shares at a substantially reduced price if a third party acquired 12.5% or more of its common stock.

“We remain committed to our proposal and a transaction with Versum, as we believe Versum is a complementary fit for our long-term strategy and our proposal will maximize value for Versum stockholders,” Merck said.

In a statement dated Mar. 11, Entegris and Versum announced the expiration of the waiting period under the US Hart-Scott-Rodino (HSR) Antitrust Improvements Act of 1976, as amended, in connection with their merger plans.

The companies said the expiration of the waiting period satisfies one of the conditions to the closing of the proposed merger, which also remains subject to other conditions as outlined in the plans announced on Jan 27, 2019.