Is it earnings, economic data, the EuroZone, or something else? MoneyShow's Jim Jubak explains what worries him the most.

For the week ahead, watch emerging markets. If you're looking for something to worry about in global financial markets, this is it. Not really weak US earnings. Yeah, that could take the US stock market down 4%, 5%. Not really a Greek exit from the euro.

That's going to create some turmoil. The real problem is, right now, in the emerging markets and that's because we've got cash flows going in two different directions and that's going to produce a lot of turbulence and the end result is some leverage on the downside and that's what you really don't like in these situations.

The two cash flows are this.

We're seeing near record or record, depending on how April plays out, cash flows from US investors into equity mutual funds and ETFs that invest in global markets.

Some of that is going to Europe. That's probably the biggest single destination but that's only about 20% of the total. The rest is going into emerging markets, China, India, whatever, looking for better returns, better valuations than you're getting in, say, the United States.

Okay, that's one cash flow so that's going that way. In the other direction, you've got cash coming out of emerging market currencies. On that level, you're seeing cash come out of these emerging market economies and that's because you're seeing the currencies in these companies go down versus the dollar, you've got worried about loan repayment, you're seeing credit stresses, all of those things. The two in combination really sort of pump up the valuations on one side and some countries, I think, were already in a bubble, the Shanghai market, I think, is in a bubble, and, on the other side, this money flowing out means that you've got a real potential for a market fall that's more than 4% or 5% because, as this money comes out, what replaces it?

If you've got enough money coming out, you've got a big leverage to the downside, so that's one of the things I'd watch right now. Cash flows, it's very interesting that you've got money from investors, retail investors a lot of it, flowing into these emerging markets finally.

On the other hand, you've got the IMF out there warning about the dangers of the global financial system from this cash flow out of these markets, hot money coming out of emerging markets. These two things together are contradictory, they worry me, and I would certainly think twice, right now, before putting money into an emerging market because of the cash that's coming out on the other side.