Apple, Amazon, Google, and Facebook, or the Gang of Four, as some call them, have come to define the glittering promise of technology. In a very short space of business time these four humble startups became the world’s most valuable and profitable companies by expertly mining a digital, online world and disrupting the way commerce had been done for decades.

Together they’ve driven technology and web connectivity into every corner of our lives through constant reinvention, ubiquitous marketing, and a voracious appetite to buy up other companies and startups on the cutting edge of the next big thing. And by making themselves indispensable to most of us in the process.

All that wealth and the unprecedented control of billions of people’s personal data have made them some of the most powerful companies in history, but it also holds major risks for all four. Consumers are growing uneasy about personal privacy and the security of their information, while governments are increasingly turning to the courts or new laws to either change the way the Big Four do business, or to force them to comply with their rules — ;especially on tax.

But technology’s relentless pace may just be their biggest threat. All four have rapidly morphed into multinational corporations, offering a growing range of consumer electronics, software, and services, often in direct competition with each other. Expect that to get even more crowded as they now jockey to win in areas as widespread as cloud computing, e-health, driverless cars, AI, Virtual or Augmented Reality, smart homes, e-commerce, entertainment, ;and mobile connectivity.

It suggests that as these prodigious companies become more alike, their battles with each other to find new sources of revenue and please ;increasingly demanding customers, will get a whole lot tougher.