To date, nearly all of my investable equity assets have been in the US market.

But I've had reservations about this from a diversification standpoint for a while.

Options I'd considered to achieve international exposure have been investing in international ETFs or international stocks.

But in recent discussions, someone brought up an intriguing third option:

Achieving international exposure by investing in US companies that do a significant amount of their business overseas. (and forgoing international stock investing completely)

This third option has raised some questions for me:

1) As an example, consider a group of US companies that collectively does 50% of its business overseas. From a diversification standpoint, is investing in that group equivalent to investing 50% of one's assets in US based companies doing 100% of business domestically and the other 50% in international companies doing 100% of their business internationally? Or does investing in US based companies doing business internationally fail to properly mitigate currency related risks compared to investing directly in international stocks?

2) Does anyone know of an easy way to find out, for a given company, how much of their business is conducted domestically vs. internationally?

3) To bring this discussion semi on-topic, does anyone know what that figure is for Berkshire?