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

Company

April 19

Weekly Gain

Vertex Pharmaceuticals (NASDAQ:VRTX)

$85.60

54%

Overstock.com (NASDAQ:OSTK)

$18.73

47%

Alkermes (NASDAQ:ALKS)

$31.27

25%

Sprint Nextel (NYSE:S)

$7.17

15%

Actions Semiconductor (NASDAQ:ACTS)

$3.14

11%

Source: Barron's.

Let's start with Vertex. The biotech soared after positive mid-stage clinical data for its treatment of cystic fibrosis in patients with a particular mutation. The group taking Vertex's combination performed considerably better than the control group.

Overstock's stock went over well after posting blowout quarterly results. The online discounter's profit of $0.32 a share was well ahead of the $0.12 the website earned a year earlier and the $0.13 analysts were expecting. Revenue also climbed by a robust 19% to $312 million during the period.

Just like Vertex, Alkermes popped on favorable clinical trial results. Alkermes' ALKS-5461 -- an oral opioid modulation drug -- showed promise in a midstage trial for the treatment of major depressive disorder. The sharp move higher excited investors, but at least one analyst felt that the move up may present an opportunity to get out. Mizuho downgraded the stock from "buy" to "neutral" later in the week.

Sprint Nextel moved nicely higher when DISH Network kicked off the week with a rival bid to acquire the country's third largest wireless carrier. DISH wants to be a major telecommunications powerhouse to match the country's two largest players that have invaded the broadband television space. This buyout saga is just beginning.

Finally we have Actions Semiconductor moving up after rolling out a new chip. The Chinese provider of mobile system-on-a-chip solutions introduced the new ATM7023 chipset, which supports the latest Android operating system, giving the company another way to get into gadgetry running the mobile operating system of choice.

Longtime Fool contributor Rick Munarriz has no position in any stocks mentioned. The Motley Fool recommends Vertex Pharmaceuticals. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.