Management regularly upgraded earnings guidance at half-year results, then beat their own upgraded guidance in the full year. Customers flocked to the cut-price telco's unlimited data plans, enabled by acquisition of Pipe Networks and other infrastructure, or were swallowed up in the acquisition of AAPT and iiNet.

But this week, TPG's share price started tumbling as if it had suffered a mortal blow. Its crime? Forecasting lower earnings than the market wanted to hear. It also warned the NBN will squeeze profit margins.

In 2014, TPG's management had forecast earnings growth of 27 per cent, and then 60 per cent growth in 2015. But now it was forecasting just 7 per cent growth.

The shares plunged as much as 27 per cent from Monday's closing price of $11.81 to the nadir of $8.61 on Wednesday. The company was worth $10 billion on Monday and $7.3 billion on Wednesday. By Friday afternoon shares were rising again and trading at $9.31.

About 63 per cent of shares in TPG are tightly held by three individuals - chief executive David Teoh and his family with 34.4 per cent, Brickworks and Washington H Soul Pattinson chairman Robert Millner with 26.8 per cent, and Bruce Gordon's Win Corporation with 1.45 per cent. None have changed their holdings this week.

However, many other shareholders decided they were only around for the good times. But is the party really over?

TPG faces unique headwinds from the national broadband network (NBN) with analysts estimating NBN taking up to $200 million from TPG's earnings through higher access costs. Chief executive Teoh negotiated such good access prices on the copper network that his wholesale costs will double when customers move to NBN's fibre.

Founder and managing director of Pipe Networks, Bevan Slattery, spoke out this week against the capacity charges on the NBN, saying it will force telcos out of business. On Friday, Communications Minister Mitch Fifield said NBN is "acutely aware" of capacity charges and flagged further price cuts.

About five million households will be connected to the NBN in the next year. Each household is an opportunity for TPG to get a new customer, but at a lower profit margin.

TPG also has plans to by-pass the NBN and many analysts expect the share price to rise in the next year.

But, the era of big growth may be over, according to telecommunications analyst at Morgans, Nick Harris.

"TPG is maturing. This is a business that has grown very very fast," he told BusinessDay.

TPG has got a unique problem with the NBN. Unlike Telstra it will not receive government compensation, and unlike Vocus its service costs will more than double, Mr Harris said. Optus' share price would be dropping too, if it were still listed in Australia.

"If you look at [TPG's] guidance, they still hit it and it was a very good number. But it was at the low end of guidance and normally they beat their guidance".

"My view is that Vocus does not have the same earnings risk that TPG has because it is already paying higher access prices," Mr Harris explained.

Meanwhile, Morgan Stanely analyst Andrew McLeod was happy with the result, but disappointed by TPG's estimate of next year's earnings. He has a target price of $10.75 for the stock. Mr McLeod was expecting to see an earnings estimate of $885 million, but got $820 million to $830 million instead.

"We estimate that [TPG] can generate an earnings margin of 26 per cent on its NBN broadband plans, above the market's long term expectations," he wrote in a note to clients.

TPG also has its own "mini-NBN" with high profit margins and could get a lot more business customers that it expects. The 'mini-NBN' is a fibre network to the basement of apartment buildings in capital cities that is designed to reach as many customers as possible for minimal infrastructure. The government tried to stop it building the network because it will cherry-pick the most profitable customers from NBN, but later decided it could proceed as long as it created a separate wholesale company and let other telcos use the fibre.

TPG will also soon get access to spectrum that could be used for mobile services or fixed wireless broadband. By using it's own spectrum and infrastructure TPG could earn higher profit margins than re-selling NBN. TPG will pay about $87 million for the spectrum.

Deutsche Bank analyst Craig Wong-Pan sees the current $8.97 share price as a bargain, with a one-year target of $11.01.

"Our positive outlook is based upon our forecast of 13 per cent earnings per share compound annual growth rate over the next 5 years from NBN-led market share gains, growth in high margin fibre to the basement services, growth opportunities in the corporate market and strong management team," he wrote in a note to clients.