The much-awaited takeover deal between India's Bharti Airtel and South Africa's Zain finally been completed today.

The total cost of the deal is $9 billion and the takeover has made Bharti Airtel the fifth largest telecom company in the world. But some experts include the risk factors associated with the deal and have valued it at $10 billion. This is in terms of the subscriber base.

Bharti Airetl is buying the African operations of Kuwait's Zain after the two entered into a deal in March this year.

The deal is the second biggest overseas acquisition done by an Indian company after Tata. As a part of the deal, all the 15 nation in Africa that have Zain operations will now come under the umbrella of Bharti Airtel.

After this, the total subscriber base of Bharti has become 180 million and its operations are spread over 18 countries including India.

The biggest challenge, say experts, before Bharti is now to streamline the operations of the two companies. It also needs to keep an eye on the loss making units of Zain.

32 per cent stake in Bharti is owned by Singapore Telecommunications and it chose Zain after MTN.