Asset manager CEOs give their top tips amid Greek fallout

The first half of the year have been characterized by severe volatility in financial markets, largely down to months of wrangling between Greece and its creditors and the ever–present specter of a Federal Reserve rate hike.

Investors have struggled to find portfolio "safe-havens," as most assets have been subject to bouts of selling. Equity markets on both sides of the Atlantic have struggled to find direction, with the likes of the German DAX up over 13 percent on a 6-month view – but down 8 percent quarter-on-quarter.

Read MoreGreece default: Why isn't gold budging?

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Yields in the U.S. and Germany have climbed, albeit with intermittent spikes of volatility, despite their traditional safe-haven status in times of economic uncertainty.

At the same time, in emerging markets, Chinese stocks have swung wildly and are currently off around 20 percent from recent 7-year highs.

Wednesday officially marks both the beginning of the third quarter and the second half of the financial calendar and with volatility unlikely to pause soon, fund management chief executives look ahead to the final six months of the year, offering investors their tips on where to look for opportunities and what to steer clear of.

US midcaps

The weakness in Greece has provided investors with a buying opportunity in the U.S., said CEO of Principal Global Investors, Jim McCaughan, particularly for small- and mid-cap companies.

Read MoreGreek letter: Are the concessions enough?

"I like small- and mid-cap, because its domestic earnings and domestic U.S. economy that is doing well. If I look at the global companies, they will continue to suffer from foreign exchange headwinds and the global slowdown. But the U.S. domestics look pretty good," McCaughan told CNBC at the sidelines of a fund management conference in Monaco.

In terms of valuations, he said relative to the 10-year U.S. Treasury, the S&P 500 looked good value.

Buy financials

Financial stocks are also worth taking a look at, according to the chief investment officer of global equities at Allianz Global Investors, Lucy Macdonald.

"I wouldn't necessarily be leaping into Greek banks at the moment, but some stock prices could be affected, while in fact the underlying businesses are not going to be affected," Macdonald told CNBC.

"So something like a UBS, in wealth management which is not really in the center of any of these risks, should be quite interesting in this environment," she added, also speaking from Monaco.

Steer clear of the 'fragile five'

In an environment where interest rates are rising, investors should be very wary of exposing themselves to the currencies, bonds and equities of the so-called "fragile five" countries – or Brazil, South Africa, Indonesia, India and Turkey, MENA Capital CEO, Slim Feriani warned.

In May 2013, after the mere suggestion of a reduction in asset purchases by then-U.S. Federal Reserve Chairman Ben Bernanke, panic spread in bond markets all over the world, in what became known as the "taper tantrum."

Read MoreWhat the bond rout means for emerging markets

"The fragile five and broader emerging markets – they can't avoid it (another taper tantrum)," Feriani told CNBC.

"I think we have had test one, which we had when the Fed started to unwind its own experiment. But we are in unchartered territory, so while 25 basis points (the Fed's first expected interest rate rise) is nothing, it is really the direction of it—where it's going and how big the hikes will be."

High-yield bubble?

The global bond market could face intensified pressure as a result of the movement in central bank interest rates, so high yield bonds (bonds with credit ratings lower than investment grade) are vulnerable, Hendrik du Toit, CEO of Investec Asset Management, told CNBC at the conference.

"Do not confuse high yield, with sustainable yield and make sure your income stream is sustainable and will survive a withdrawal of quantitative easing," he said.

"I don't think there is necessarily a bubble, but a vulnerability given investor expectations and the reality on the ground. If you have large amounts of money being withdrawn in fear, then any asset market can collapse. If you look at bubbles, what really is overvalued is high quality government bonds, but we don't expect any immediate issue there," du Toit added.

Watch out for China

China had got firmly into a bubble reminiscent of the 1999 internet boom in the U.S., McCaughan said, but the amount of liquidity chasing Chinese equities made it a "wild card".

Read MoreChina stocks hit 7-year high, but where's the growth?

"The wild card out there is, do the professional investors, the Western investors get more into China – they are very underweighted there," he said.

"If MSCI and FTSE continue with the gradual moves to get them into the indexes there, then I think the Western investors will have to increase. So I don't think it's a buy yet, I don't think it's gone down enough out of bubble territory , but China is one of the big wild cards that need to watched in world equity markets."