It’s been a rollercoaster day on the S&P/ASX 200 (Index: ^AXJO) (ASX: XJO) today, although the market does look like finishing up at the close.

In late afternoon trading the index was at 5,283 – up 0.2%.

These four companies have seen their share prices soar…

Adacel Technologies Limited (ASX: ADA) has seen its share price gain 4.9% to $2.885. Adacel develops simulation software and air traffic control trainers for a variety of customers including defence and obviously airports. The company reported strong performance from new and expanded orders in April, although I note two directors and a substantial shareholder have been selling shares in May. Adacel was nominated as a stock with huge potential by Motley Fool General Manager Bruce Jackson in November 2015 – when the share price was at $1.40.

South32 Ltd (ASX: S32) has seen its share price rise 4.2% to $1.72, which is a remarkable comeback considering the miner still faces heavy headwinds in the form of low commodity prices for many of its products. South32 saw its share price sink as low as 87 cents in January.

Spinoffs often outperform their parents, and South32 certainly has done that compared to BHP Billiton Limited (ASX: BHP) over the past 12 months. South32’s share price is down 8.7%, while BHP has lost 34% of its value.

Appen Ltd (ASX: APX) share price is up 4.1% to $2.54. The translation, speech and search technology company has seen its share price soar more than 250% over the past year, after quadrupling its net profit in FY 2015. Having offshore earnings has helped as has the company’s forecast of earnings growth in the high teens for the 2016 financial year (FY16).

REA Group Ltd (ASX: REA) share price has jumped 3.7% to $59.72. The real estate portal company is expanding its operations into Asia and the US and results so far indicate those two markets could be bigger money winners than realestate.com.au in the years ahead. REA has also branched out into complementary services, acquiring flatmates.com.au in May. Flatmates.com.au – as you might imagine – is a site for share accommodation.

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Motley Fool writer/analyst Mike King doesn't own shares in any companies mentioned. You can follow Mike on Twitter @TMFKinga

The Motley Fool Australia has no position in any of the stocks mentioned. We Fools may not 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. This article contains general investment advice only (under AFSL 400691). Authorised by Bruce Jackson.