The S&P/ASX 200 (Index: ^AXJO) (ASX: XJO) may have had a great month, but the same cannot be said for all shares on the Australian market.

The following two shares have not had a great time of late, but their huge declines could possibly make them bargain buys now in my opinion. Here they are:

iSentia Group Ltd (ASX: ISD)

It hasn’t been a great year for shareholders of this global leader in the delivery of crucial business intelligence. Its share price has lost a third of its value in 2016 after investors exited the technology company en masse earlier in the year.

Despite the company producing strong half year underlying net profit after tax and amortisation growth of 22%, investors appear to have concerns over its prospects in the Asia market. Like many fledgling Australian companies, the Asia market is seen as the driver of long-term growth.

But although its Asia segment delivered over 20% revenue growth in the first half, this growth lessens significantly once you factor in the substantial depreciation of the Australian dollar during the period.

After such a steep fall I believe the share price will get a huge lift if the company can demonstrate strong organic growth in Asia when it reports its full year results on August 24. Whilst I would approach it with a little bit of caution, I do feel there is a strong possibility of a great long-term investment with iSentia.

Kogan.com Ltd (ASX: KGN)

It’s fair to say the online retailer has had a terrible start to life as a listed company. Its share price plummeted immediately after hitting the boards and still sits down by around 13% despite a recent rally.

But I do believe it is well positioned for long-term growth. According to data released by National Australia Bank Ltd. (ASX: NAB) on Wednesday, Australians spent 13.5% more online in the 12 months to June 30, than they did in the prior corresponding period.

The Online Retail Sales Index revealed online spending increased to $20.1 billion for the period, roughly equivalent to 6.8% of bricks-and-mortar retail spending. As more and more consumers switch to buying online, I expect Kogan to see strong levels of organic growth.

Personally, I don’t believe it will be long until Kogan’s share price breaks through its $1.80 IPO price. For this reason I see it as a great long-term investment today, just as long as Amazon doesn’t open a local online store in Australia. If that were to happen, then I would head for the exits immediately.

Before investing in either of these shares I would highly recommend taking a look to see if you own any of these three rotten ASX shares. Each could be harming your portfolio and stopping it from reaching its full potential.

3 Rotten Shares to Sell, and 1 to Buy Today

After a double-digit rally for the ASX since 2016 lows, investors should be on high alert. You'll find a full rundown below of 3 shares we think you should avoid today plus one top pick worth buying, even if the market turns south and the RBA keeps rates at an "emergency low." Simply click here to uncover these stocks.

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Motley Fool contributor James Mickleboro has no position in any stocks mentioned. 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.