The S&P/ASX 200 (Index: ^AXJO) (ASX: XJO) opened lower today, but has fought back and is currently clinging onto a small 0.3% gain to 5,340 points.

This is quite impressive considering the large declines in the energy and materials sectors which are both nursing losses of almost 3% today.

There have been four shares in particular that have acted as a drag on the market today. Here’s why:

BHP Billiton Limited (ASX: BHP) shares are down over 4% to $17.62 today following a terrible night for commodity markets. This heavy fall came as a result of both iron ore and oil prices falling overnight. Of course, BHP Billiton was not alone. Rio Tinto Limited (ASX: RIO) and Fortescue Metals Group Limited (ASX: FMG) have suffered from steep declines today as well for the same reasons.

BHP Billiton shares are now down by just under 2% in 2016.

Greencross Limited (ASX: GXL) has suffered a sharp decline of almost 7% to $7.05 today. This appears to be related to recent news that Quadrant Private Equity has sold its stake in the pet care group. Greencross had been subject to a takeover bid of $6.45 per share, with many speculating an improved offer was coming. But by selling their stake it would appear that Quadrant is not interested in a takeover now.

Despite this Greencross shares are still up 8% in the last 12 months.

Prophecy International Holdings Limited (ASX: PRO) saw its share price drop again today, this time by over 5% to $1.18. The shares have been under a lot of selling pressure since it downgraded its 2016 full year forecast last week. The IT security company is now expecting EBITDA to come in between $5 million and $7 million, compared to its earlier forecast of $8.9 million.

Prophecy has now lost almost 39% of its market value since the turn of the year.

SEEK Limited (ASX: SEK) has not had the best of days today, dropping almost 4% to $16.54. Whilst there was no news released today, the ANZ Job Advertisements data for April was released yesterday showing job advertisements down 0.8% month-on-month. Economists had been expecting a small gain. It is worth noting that Freelancer Ltd (ASX: FLN) jumped by almost 4% today, possibly suggesting that the job advertisements data is not related to SEEK’s share price fall.

SEEK has still managed to gain over 7% so far in 2016.

The technology that's going to REPLACE the Internet is already here...

Dollar for dollar, insiders are calling it one of the biggest new markets in the history of modern business... NOW is the time to get in on the hush-hush industry that could be poised for growth of over 4,463%+ by 2020... And the 1 ASX stock that stands to grow YOUR money right alongside it! Simply click here to learn its name.

HOT OFF THE PRESSES: Motley Fool’s #1 Dividend Pick for 2017!

With its shares up 155% in just the last five years, this ‘under the radar’ consumer favourite is both a hot growth stock AND our expert’s #1 dividend pick for 2017. Now we’re pulling back the curtain for you... And all you have to do to discover the name, code and a full analysis is enter your email below!

Simply enter your email now to receive your copy of our brand-new FREE report, “The Motley Fool’s Top Dividend Stock for 2017.”

By clicking this button, you agree to our Terms of Service and Privacy Policy. We will use your email address only to keep you informed about updates to our website and about other products and services we think might interest you. You can unsubscribe from Take Stock at anytime. Please refer to our https://www.fool.com.au/financial-services-guide">Financial Services Guide (FSG) for more information.

Motley Fool contributor James Mickleboro has no position in any stocks mentioned. The Motley Fool Australia owns shares of Prophecy International Holdings Ltd.. 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.