The Impact picked up Sinovic from SKC last week but have sent the 24-year old back to Livestrong Sporting Park with allocation money in exchange for 31-year old midfielder Arnaud.
"Davy is a fierce competitor, an incredible leader and a hard-working player," said Impact head coach Jesse Marsch. "He is a proven winner in MLS. He will help us establish a winning environment with our team. His acquisition makes us a better team."
"Following the acquisition of defender Nelson Rivas, we have added to our roster another key player in a vital position," said Impact sporting director Nick De Santis. "Davy Arnaud will become a part of the team's nucleus. We are very pleased to have acquired him."