Most long-term investors would consider a short-term multi-bagger a bit of a fluke, but we’d all be happy to take one if it should come along. Over the past year we’ve seen some big risers among the companies listed on AIM, and today I’m looking at three of them and asking if they can continue upwards.

Great time for small oilies?

The rising price of oil is making American oil shale and fracking operations look attractive again, and prices reaching the $50 per barrel level have helped push Pantheon Resources (LSE: PANR) shares upwards. Priced at 186p today, Pantheon shares have soared a stunning 680% in just 12 months!

The company, operating in East Texas, told us in its latest update that planned fracking is underway at its VOS#1 well and that drilling at its VOBM#2H well has commenced, together comprising the company’s fully-funded 2016 programme. That “fully funded” bit is crucial, and with the successful completion of a $30m share placing in March, Pantheon isn’t facing the liquidity pressure crippling some other small explorers. In fact, it’s forecast to generate profits in the year to June 2017, after a modest loss expected for this year.

As always, oil explorers like this are almost impossible to value at this stage. But with Pantheon shares on a P/E multiple of 37.5 for its first year of profit in 2017, if its wells are as productive as hoped and if the price of oil keeps on up, there could be more to come.

Banking on gold

Another commodity recovery, that of gold, is behind the 245% rise in Trans-Siberian Gold (LSE: TSG) shares over the past year. At approximately $1,240 per ounce, the shiny stuff is a long way up from its start-of-year low of around $1,050, and that’s geared up the Trans-Siberian share price to 38p.

Interest rates remaining low for longer than many had hoped have helped whet investors’ appetites for gold, and the likely economic turmoil that a UK EU exit (which would surely have adverse effects way beyond these shores) would cause will have sent many in the direction of safety.

The trouble is, even though Trans-Siberian shares are on low P/E valuations, the company’s cost of production has been variable. The cost of sales of $712 per ounce of gold recorded for the first half last year was 44% lower than the previous year, which is good, but such volatility can work both ways. If costs rise again and gold prices fall, profits could be squeezed.

Queuing for profits

My third is Accesso Technology (LSE: ACSO), a company designing and supplying virtual queuing systems for amusement parks and similar venues. Accesso, previously known as Lo-Q, has been a growth success over the past few years, with a 127% share price rise in 12 months adding to earlier rises to provide a 640% gain over five years.

The downside for me, though, is that the shares appear to be fully valued against future growth expectations. Accesso’s results announcement for 2015 includes details of continuing new contract wins, with Blackpool Pleasure Beach and the One World Observatory in New York among them.

But we’re looking at a P/E of 42.5 based on this year’s forecasts, dropping only to 35.2 for 2017, and PEG ratios in excess of the 0.7 or less that growth investors typically favour. It’s not one for me right now.

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Alan Oscroft has no position in any shares mentioned. The Motley Fool UK has no position in any of the shares mentioned. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.