An investor’s time horizon is one of the biggest determinants of how an investor’s portfolio should be constructed.

Younger investors have the advantage of time on their side and this means they can afford to have a higher proportion of their portfolio in speculative or higher risk shares.

On the other hand, capital preservation will be more important for older investors and this means only a small proportion of their portfolio should ever be allocated to speculative shares.

While most people would associate speculative shares with unprofitable biotechnology and exploration companies, I think speculative shares can apply to a whole range of companies from different industries.

With that in mind, here are three shares that I would classify as speculative that could be worth a closer look for risk tolerant investors:

Cash Converters International Ltd (ASX: CCV)

Cash Converters is actually quite profitable, but I would still put it in the speculative basket for now.

The shares have been absolutely pummelled over the past couple of years as a result of the company having to deal with a wave of problems ranging from class actions, negative press and legislative changes.

This uncertainty is still lingering around the company at the moment and investors are now waiting to see how the latest Queensland class action claim plays out.

If Cash Converters can come out of the case relatively unscathed then I think the shares will be significantly re-rated as the underlying business is still growing quite strongly. The shares are currently trading on a price-to-earnings ratio less than 7, assuming the company can match its first half net profit after tax figure of $15.9 million.

Senetas Corporation Limited (ASX: SEN)

Senetas is a small-cap technology company that provides high-speed data encryption hardware designed to protect the digital information of governments and businesses.

Cyber security is becoming an increasingly important issue for companies and Senetas is building a solid reputation in the segment.

The shares have been punished since the start of the year following a profit downgrade and now trade at 10.5 cents a share – down more than 52% from its 52-week high of 22 cents.

Although profits are expected to remain flat for the remainder of FY16, profit growth could accelerate in FY17 as a number of new products are expected to be launched.

Mobile Embrace Ltd (ASX: MBE)

Mobile Embrace is another small-cap technology company that operates in the growing mobile advertising and payments market.

The company has partnered with some of the world’s largest consumer brands and telecommunications companies and this has resulted in extraordinary revenue growth over the last few years.

Unfortunately, this hasn’t been reflected in Mobile Embrace’s share price with some investors feeling disappointed with slower-than-expected profit growth.

Despite this, I think Mobile Embrace is well placed to maintain its growth trajectory and this should eventually be reflected in a higher share price.

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Motley Fool contributor Christopher Georges owns shares of Cash Converters International Limited. 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.