The past five years have been good to BT (LSE: BT) investors as the telecoms shares have gained nearly 120% in value. While this bull run may continue, there are some speed bumps on the horizon shareholders should be aware of.

First is increased government scrutiny of Openreach, the subsidiary that controls nearly the entire last mile physical broadband and landline infrastructure in the UK. This division is critical to BT as over the past fiscal year Openreach provided 40% of group EBITDA, despite accounting for only 11% of revenue.

The government, competitors and consumers alike have bemoaned the low quality of the UK’s broadband network and blamed BT for not reinvesting enough of Openreach’s profits in the physical infrastructure. While the government didn’t head loud calls to split off Openreach in its latest review, this remains a possibility in the future.

The second worry on the horizon in my eyes is BT’s push into becoming a major player in ‘quad-play’ packages. This is a highly competitive space that requires investing heavily in the likes of sports rights (nearly £2bn on football alone) and mobile phone services (£12.5bn for EE). This move could pan out, but it does shift BT’s focus from its traditional strong point and any change to Openreach’s status would be devastating while the company invests so much in this new business line.

Margin boost

Few companies have taken advantage of the internet’s ability to democratise information more than property search giant Rightmove (LSE: RMV). Shares of this online database have risen by 290% over the past five years due to its dominant market position and industry-leading margins. Management leveraged 77% market share over the past year into a 50 basis point improvement in underlying operating margins to an astounding 75%.

Continued margin improvement and the relative failure of, the estate agents’ attempt to wrest back market share, show there’s little danger to Rightmove’s business internally or from competitors. However, the company is still vulnerable to any shifts in the housing market and the recent bull run in home values will eventually end. However, it’s impossible to predict when this will happen and Rightmove remains a solid company whose dominant position and cash flow is mightily appealing.

Tech spend drives growth

Domino’s Pizza (LSE: DOM) has been a quiet winner over the past five years as shareholders have enjoyed a 165% jump in share prices alongside a 68% rise in dividend payouts. While a revamped pizza recipe from the American headquarters has certainly played a large role in this success, the company has done well to expand its market share through innovative means.

Foremost among these is a focus on technology that has paid off with a full 67% of orders now coming through e-commerce. This helped like-for-like sales in the UK jump 11.7% last year. Combined with the addition of 61 new stores, 23% operating margins due to the company’s asset-light franchisee business model and its position as the largest pizza delivery company in the market, Domino’s should continue to thrive as long as consumer spending holds steady or increases. While shares may be pricey at 27 times forward earnings, I see little reason to believe shares won’t live up to that valuation.

The growth these three companies have posted over the past few years is certainly impressive, but it's nothing compared to the 19 consecutive years of sales growth at the Motley Fool's Top Growth Share.

And, even after share prices jumped 200% over the past five years, the Fool's top analysts believe the company could triple again in the coming decade.

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Ian Pierce has no position in any shares mentioned. The Motley Fool UK has recommended Domino's Pizza and Rightmove. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.