The Investment Company Institute says President Donald Trump's tax bill impacts most foreign investments in U.S. stocks, according to documents seen by CNBC.

Trump's spending bill includes a "revenge tax" to countries that levy "unfair foreign taxes" on U.S. companies. Here's what to know about Section 899.

The Investment Company Institute says President Donald Trump's tax bill impacts most foreign investments in U.S. stocks, according to documents seen by CNBC.

Known as Section 899, the measure could cause companies to avoid investing in the the U.S. out of concern they could face steep taxes.