I really don't know, I don't follow the currency markets much.
I trade the dollar, but that is just a technical trade based on the same things I always use, adjusted a bit for the unique "personality" of the dollar and how it tends to trade.
I don't have any hard numbers on this, but my feeling is that foreign investors are major players in the treasury markets, but much less so in the equities markets. I don't think they will move the equities markets in a big way.