Bitcoin began the week on a down note, declining as much as 8.7 percent, pushing the biggest cryptocurrency’s decline for March to about 25 percent.

Twitter Inc. confirmed today that it’s banning advertisements for initial coin offerings and token sales on its social-media platform. The decision comes after Facebook Inc. banned cryptocurrency ads in January and Alphabet Inc.’s Google said it would ban such ads starting in June, as part of a broader effort to crack down on deceptive and misleading advertising on their platforms.

After reaching a record high of almost $20,000 in December, Bitcoin has slumped about 60 percent as investors reconsider the prospects of the digital currency and regulators around the world increase scrutiny.

The U.S. Securities and Exchange Commission sent a number of subpoenas earlier this month to ICO teams it suspects are breaking securities regulations, and it has warned since July that some of the offerings may be breaking securities regulations. Twitter said on March 7 that it was implementing measures to prevent crypto scams.