Brexit Minister Dominic Raab and 3 more of PM Theresa May's ministers resigned Thursday to protest her proposed Brexit agreement that they say will make the UK a "vassal state" of the EU for years.

A proposed "backstop" arrangement that would create a common EU-NI customs arrangement is a major sticking point. The NI DUP has threatened to withdraw its support of Ms. May - which is necessary to keep her government in power - if NI would be treated differently from the rest of the UK post-Brexit.

These events raise possibilities of a no-deal Brexit, and of the fall of Ms. May's government.

Sterling and stock values plunged on the news.

Stay tuned.