The 5 most valuable US tech companies are now worth more than $5 trillion after Alphabet's record close

• Google-parent Alphabet soared to a $1 trillion valuation Thursday, pushing the total value of the five biggest tech companies to a record $5 trillion.
• Apple and Microsoft both boast market caps above the four-comma threshold, while Amazon sank to a $930 billion valuation after first breaching the level in September 2018.
• The record-high valuation for Big Tech comes amid heightened regulatory scrutiny around data privacy and calls from governments around the world to break up the massive companies.
• Here are the five highest-valued tech stocks, ranked in ascending order.
• Visit the Business Insider homepage for more stories.

Google-parent Alphabet on Thursday became the fourth US company to reach a $1 trillion market valuation, pushing the total value of the five biggest tech companies to a record $5 trillion.

Apple and Microsoft sit well above the $1 trillion level, surging through the new year after massive gains in 2019. The S&P 500's information tech sector, which includes the two aforementioned companies, is up more than 5% year-to-date, outperforming all other groups in the benchmark index.

Amazon previously held a market value above the four-comma threshold but has since sank to roughly $930 billion. Facebook sits at the lowest valuation among the group of five with a market cap of about $630 billion. Including Facebook in the group drives Big Tech's collective value above $5.2 trillion.

CNBC first reported on the milestone valuation for Big Tech.

The record-high valuation for Big Tech arrives amid heightened scrutiny from regulators and US legislators. Calls to break up the most valuable tech firms have taken center stage at congressional hearings, Democratic primary debates, and in governments abroad as many view the companies as reaching monopolistic levels of influence.

The European Union's antitrust regulators recently homed in on Big Tech following the Cambridge Analytica scandal, and the group is now grilling Google over its data collection policies. State attorneys general in the US are also investigating the search engine giant, yet the months of regulatory pressure haven't held shares down. Alphabet jumped more than 30% in 2019 and is already up nearly 9% in the new year.

Here are the five highest-valued tech companies, ranked in ascending order by market cap. Data is as of market close on January 16.