Will Vietnam stocks resume their rally in 2015?

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Vietnam shares have managed respectable gains this year, but it isn't clear whether expectations of solid economic growth will translate into another leg higher.

The economic outlook certainly appears fairly bright.

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"We see Vietnam achieving its impressive macro mix target of 6.2 percent growth and below 5 percent inflation in 2015," Deutsche Bank said in a note, although it highlighted some concerns over debt overhangs and risks from China's economic slowdown.

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Shares have responded positively as well, with the VN index up nearly 13 percent so far this year, after rising around 22 percent in 2013. But the index is down around 10 percent from its September peak.

Market concerns

It isn't clear if the positive economic picture will translate into continued stock gains, especially amid concerns over whether the market's structure is really ready for prime time.

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For one, fund managers are concerned about the implications of Mondelez International buying an 80 percent stake in a subsidiary of listed Kinh Do Corp., a deal flew under the radar of restrictions on foreign ownership.

"It makes absolutely no sense where you have a market where you can buy 100 percent of the assets of a listed company by those assets being put into a subsidiary, but only 49 percent of a listed entity. What's the point of a listed entity," asked Kevin Snowball, CEO of PXP Vietnam Asset Management. "There is a danger that if they allow these subsidiary takeovers, the market essentially becomes a way of advertising wares for sale."

Snowball is also concerned that plans to list state-owned enterprises are proceeding slowly and at elevated pricing.

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In November, Vietnam Airlines raised around $51.3 million in an initial public offering planned since 2008. Not only was the offering only around 3.5 percent of the company, but the bulk was purchased by two Vietnamese banks, with no foreign institutional investors participating. The shares aren't expected to begin trading on an exchange until around March.

"If they want [the stock market] to be more than an alternate casino for retail punters, then they need to foreign institutions more involved because there is no local institutional investor base to speak of," Snowball said. "Increasing supply via some successful and sensibly priced IPOs and increasing access to foreign investment [is needed to] become a more serious market."

Investors hesitant

The concerns are keeping some institutional investors out of Vietnam.

"Vietnam at this point in time is still very much a private equity market. It's still not ready for institutional investors," said Jalil Rasheed, director for Southeast Asia at Invesco, citing difficulties including how long it takes to settle trades and getting approval to swap currency.

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Like Snowball, Rasheed is also concerned that the market doesn't have enough stocks available.

"The top ten stocks make up about 80-90 percent of the index and they're largely state-owned enterprises," Rasheed said, adding corporate governance isn't up to the standards of much of Southeast Asia.

There's another factor which could weigh on Vietnam's shares: it's an oil producer. Since this summer, Brent has fallen from above $115 per barrel to around $66.08 in Asian trade Tuesday, with many oil analysts predicting prices will continue to slide.

PetroVietnam Gas, the largest company by market capitalization, has been leading the market down recently, Snowball said.

—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1