Investors have shunned Vodafone and TPG after the competition watchdog raised concerns about the merger between the two telco giants.

The ACCC is concerned that if the two were to form one $15-billion company, it could mean higher mobile prices for consumers.

TPG shares fell as much as 18.9 per cent after the ACCC, which has the power to block the merger, said it could reduce competition.

Shares in Hutchison Telecommunications – which owns a 50 per cent stake in Vodafone – were even more heavily hit, falling as much as 35.7 per cent.

ACCC Chair Rod Sims tells John Stanley he’s concerned the merger would remove TPG’s incentive to price aggressively in an effort to rival Telstra, Optus and Vodafone.

Click PLAY below to hear the full interview