Facebook CEO and founder Mark Zuckerberg testifies during a US House Committee on Energy and Commerce hearing about Facebook on Capitol Hill in Washington, DC, April 11, 2018.

Facebook and Amazon each spent more than $4 million on lobbying in the second quarter of 2019 as antitrust regulators have taken steps to scrutinize Big Tech.

The two firms outspent their tech peers including Google, which was the biggest tech lobbying spender of 2018. Google reported $2.9 million in lobbying spend for the quarter, according to newly released lobbying disclosures, continuing a trend of reduced spending on such activity. Earlier this year, Google fired several of its biggest lobbying firms as it restructured its policy operations, The Wall Street Journal reported in June.

Facebook spent $4.1 million on lobbying activity in the second quarter of 2019, outspending almost all other tech firms. Amazon followed closely behind, spending just over $4 million, although its filing does not include lobbying spend for its cloud division, Amazon Web Services, which could put it in the lead.

The hefty spending comes as the Federal Trade Commission and the Department of Justice have begun to solidify their scrutiny of the nation's largest tech firms. Tech stocks stumbled in June when reports emerged claiming the two agencies divided oversight of Facebook, Amazon, Apple and Google parent company Alphabet. Tech lobbying spend for the quarter rivals traditional big spenders like Pfizer and Boeing, which spent $2.9 million and $3.9 million, respectively.

Tech lobbying spend for the quarter covered a wide range of issues for both companies. Amazon put resources toward issues related to immigration, trade policy and data privacy, for example, according to its filing. Facebook spent time on issues related to tech competition, online advertising, and artificial intelligence, among others, its filing stated.

Facebook and Amazon both put more cash toward lobbying in the quarter compared to the same period last year. Facebook spent just $3.7 million in lobbying activities in the second quarter of 2018, while Amazon spent $3.5 million.

Apple also upped its lobbying spend in the second quarter compared to last year, spending $1.8 million compared to $1.6 million during the same quarter in 2018. Microsoft spent $2.7 million on lobbying activity for the quarter, compared to $2.6 million in the second quarter of 2018.

Qualcomm was also among the top spenders in the quarter as it spoke up on trade issues and 5G, spending $1.9 million for the quarter.

— CNBC's Aditi Roy contributed to this report.

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