The last 30 days has been incredibly kind to shareholders of companies such as Retail Food Group Limited (ASX: RFG) and Treasury Wine Estates Ltd (ASX: TWE). Both of these shares have delighted their respective shareholders by putting on share price gains of around 20% during this time.

Unfortunately for the shareholders of the following three shares, things haven’t been as kind. Their respective shares have been beaten down in the last 30 days. But are they bargain buys now or still best avoided?

Aconex Ltd (ASX: ACX)

This software-as-a-service provider has seen its share price drop 22% in last 30 days following a full year result which fell short of market expectations despite the quadrupling of net profit. Its increasingly popular construction collaboration platform is being used by some of the biggest names in the $10 trillion a year construction industry. The platform transforms the way project teams work together to make the process fairer, easier, and more efficient for everyone. According to a recent presentation management stated that it believes its platform can accelerate the pace of product delivery and help build five hospitals for the price of four. With results like that it’s not hard to see why it’s so popular. I believe there is a lot of growth ahead and this sell off has made Aconex a great buy today.

Medibank Private Ltd (ASX: MPL)

The share price of this leading health insurer has plummeted 18% in the last 30 days. Despite posting a 46.4% jump in profits to $417.6 million, the market has focused on management’s acknowledgement that member switching between health insurers meant a loss of market share in the second half. This led to a disappointing outlook for FY 2017 and investors heading to the exits in their droves. With its shares now changing hands at 16x earnings and providing a fully franked 4.5% dividend, Medibank Private could be worth a second look.

QBE Insurance Group Ltd (ASX: QBE)

Since releasing a disappointing interim result which revealed a sharp drop in profits, this insurance giant’s shares have lost around 15% of their value. In addition to this the market clearly wasn’t impressed by the fact that QBE Insurance downgraded its outlook for full year gross written premiums by close to US$500 million. Although the company has taken action to arrest this decline, I still feel that a turnaround is someway off. As a result I think Suncorp Group Ltd (ASX: SUN) would be the better option for investors looking for exposure to the insurance sector.

Do you own either of these three wealth destroying shares in your portfolio? Now might be a great time to swap them out if you ask me.

3 Rotten Shares to Sell, and 1 to Buy Today

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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.