Big tech is getting bigger.

Apple, Alphabet, Microsoft, Amazon and Facebook, the world's five most valuable public companies, added $181 billion to their combined market value on Friday.

Investors piled into the group a day after Alphabet, Microsoft and Amazon reported better-than-expected earnings.

For the stock market, it was more of the same. Those five companies have gained almost $900 billion in market capitalization over the past year. They've each outperformed the S&P 500 in 2017, and have been the top contributors to the index's 15 percent gain.



Despite potential political and regulatory pressures on Google, Facebook and Amazon and loud voices of concern about the tech giants hurting competition and controlling too much of our data, the stock moves reflect financial performance. And the performance is staggering.