Just one day after Facebook responded to an ongoing anti-Semitic advertising controversy, both Google and Twitter have become embroiled in the same debate concerning oversight and moderation on the web’s pervasive and powerful ad platforms.

Google’s ad tech, the main contributor to its parent company Alphabet’s roughly $100 billion in annual revenue, lets advertisers target search users by what phrases they type into the query field. A report from BuzzFeed News today found that Google’s ad platform permitted advertisers to sell ads next to anti-Semetic and racist queries, including “Jewish parasite,” “the evil Jew,” and “black people ruin everything.”

Silicon Valley’s ad platforms have seemingly little to no oversight

In the case of Google, the company’s ad platform even suggested potential advertisers run ads next to other, similar hateful phrases, like when it suggested an ad next to the phrase “jewish control of banks” when one types in “why do jews ruin everything.” In addition to seeing these suggestions when it investigated Google’s ad platform, Buzzfeed also purchased ads and ran a live campaign before alerting Google, which promptly disabled a number of the keywords involved.

“Our goal is to prevent our keyword suggestions tool from making offensive suggestions, and to stop any offensive ads appearing,” Sridhar Ramaswamy, Google’s senior vice president of Ads & Commerce, told The Verge in a statement. “We have language that informs advertisers when their ads are offensive and therefore rejected. In this instance, ads didn’t run against the vast majority of these keywords, but we didn't catch all these offensive suggestions. That's not good enough and we’re not making excuses. We've already turned off these suggestions, and any ads that made it through, and will work harder to stop this from happening again."

Now, just hours after this recent Google revelation, The Daily Beast is reporting that Twitter too lets advertisers target users interested in hateful words and phrases, including the N-word, “wetback,” “Nazi.” While reports of using similar targeting methods on Facebook and Google’s platforms made clear that there were only a few thousand people in the US that would see these ads, Twitter’s platform appears more far-reaching.

The Daily Beast, which briefly ran its own ad campaign to test the company’s tools, says Twitter’s platform shows 18.6 million accounts “likely” to engage with the word “Nazi,” while another 14.5 million users might be drawn in by the N-word. For Twitter, the process seems entirely automated and there appear to be no safeguards in place — The Daily Beast tried a number of different hateful words and phrases and none were blacklisted by Twitter’s tools.

Tech companies are woefully unequipped to handle hate speech online

In a statement given to The Verge, Twitter says, “The terms cited in this story have been blacklisted for several years and we are looking into why the campaign cited in this story were able to run for a very short period of time. Twitter actively prohibits and prevents any offensive ads from appearing on our platform, and we are committed to understanding why this happened and how to keep it from happening again.”

On Saturday, Twitter issued a new statement saying that it had fixed an error that allowed ads to be targeted against hate speech. “We determined these few campaigns were able to go through because of a bug that we have now fixed,” the company said in a statement to The Daily Beast.

There is now mounting concern within Silicon Valley and beyond that there is a severe lack of oversight inherent in the tech industry’s all-powerful ad platforms. Between Facebook and Google alone, these platforms capture 90 cents of every new ad dollar spent on the web and act as the economic engine of the world’s most popular free apps and services. That these companies have been catering to bigots, no matter how obtusely, is now of national concern following the real-world mobilization of hate groups and incidents like the Charlottesville, Virginia rally, which attracted neo-Nazis and white nationalists and left one counter-protestor dead.

This most recent ad controversy began picking up steam when The Washington Post revealed earlier this month that fake accounts with ties to a Russian troll farm, one notorious for peddling Russian propaganda, purchased $100,000 worth of political ads to try and influence the US presidential election last year.

Facebook’s obliviousness in this case prompted ProPublica to investigate. That resulted in a bombshell report on Thursday showing how Facebook’s ad platform allowed nearly any self-reported information field on someone’s profile, like “field of study” or “job title,” could be used to target users with ads, even if that field contained phrases like “Jew hater” and “Hitler did nothing wrong.” ProPublica also ran its own ad campaign before Facebook responded late yesterday by temporarily disabling the ability for advertisers to target users by easily manipulated fields like education and employer. The company says it “has more work to do.”

Update at 4:10PM ET, 9/15: Added new statement from Google.

Update at 7:13PM ET, 9/15: Added new statement from Twitter.

Update at 12:59PM ET, 9/16: Added new statement from Twitter.