What's better than momentum? Mo' momentum. Let's take a closer look at five of this past week's biggest scorchers.

Company

March 28

Weekly Gain

Arotech (ARTX)

$5.82

38%

Conn's (CONN -0.27%)

$38.78

16%

Petrobras (PBR -0.70%)

$13.18

14%

Yongye (YONG.DL)

$6.80

13%

Nu Skin (NUS 2.75%)

$83.06

11%

Source: Barron's.

Let's start with Arotech. The provider of defense and security products is starting to gain steam for its lithium-ion battery division. It kicked off the week by announcing orders of more than $2 million for batteries and chargers. A SeekingAlpha contributor then posted a blog entry playing Arotech up as an unheralded play in lithium-ion batteries, slapping a $16 price target on the shares. The volatility should continue. Arotech will post quarterly results after Monday's market close.

Conn's moved higher after posting quarterly results. The consumer-electronics retailer posted sales and profitability that fell just short of Wall Street expectations, but investors looked past the income statement shortfall after the chain revealed that its delinquency rate was improving. Conn's had spooked investors earlier this year after reporting that the number of deadbeat customers were on the rise. Now Conn's is pointing to improving collections.

Things are heating up in Brazil, and not necessarily in a good way. Inflation continues to grow faster than the economy, its president's approval rating is at its lowest level since last summer, and Standard & Poor's just downgraded the country's credit rating. However, Brazilian stocks still rallied on the week, led by bellwether Petrobras. The bullish thesis here is that political change will take place in October's presidential election, and that should include economy-boosting reforms. It also only helped Petrobras that crude oil prices moved higher on the week. 

While Brazil was rocking this past week, Chinese stocks continue to slide. This has prompted many fallen growth stocks to go private. The latest entry this week is Beijing's Yongye, which received a sweetened buyout bid from a group led by its CEO. The distributor of crop nutrient products will now go private at $7 a share, up from the original privatization offer of $6.69 a share.   

Finally we have Nu Skin moving higher after getting off easy in the aftermath of an investigation conducted by Chinese regulators. The provider of nutritional and skincare products will have to pay just two small fines. Nu Skin is also cleared of making any major violations.