Argentina's Tecpetrol, part of the Techint Group, said on Thursday it would invest US$2.3 billion in the Vaca Muerta shale fields through 2019, the largest announcement in the formation in years. Tecpetrol said in a statement the investment was made possibly due to measures from President Mauricio Macri's government, including a deal with labor unions earlier this year and a definition of price supports this month.