If you'd invested in: Taptica and Microsaic Systems

Taptica (Aim: TAP) is an Israeli digital marketing company with offices in San Francisco and New York. The company has recently moved its efforts away from display ads on desktop computers to focus on advertising on smartphones as traffic and revenue moves to handheld devices. As part of the transition, it changed its name from Marimedia to Taptica. After listing on Aim in 2014, the shares fell sharply, but in the last year they have risen by more than 140%.

Be glad you didn't

Woking-based Microsaic Systems (AIM: MSYS) makes mass-spectrometry instruments for the pharmaceutical industry, which it claims are much smaller and more cost efficient than traditional equipment. It was established in 2001, and does not currently make a profit, with a pre-tax loss of £1.7m in the six months to 30 June, a performance the management called "very encouraging". Shareholders don't seem to agree: the shares have fallen by more than 80% in the last year.

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