So far in 2018 the S&P/ASX 200 (Index: ^AXJO) (ASX: XJO) has had a reasonably unspectacular time and has managed to carve out a gain of just 2.3%.

Fortunately, this hasn’t stopped some shares from storming higher. In fact, the three shares listed below have just about doubled in value since the turn of the year.

Is it too late to invest?

The Nearmap Ltd (ASX: NEA) share price is up a remarkable 136% year-to-date. A good portion of these gains have come in the last week following the release of the geospatial map technology company’s preliminary full-year results. That release revealed record portfolio growth for the 12 months ended June 30. Annualised contract value exceeded the company’s guidance and reached $66.2 million at the end of FY 2018. This was an increase of 41% on the prior year and was largely the result of stronger than expected growth in the massive U.S. market. I think Nearmap is well worth a closer look after this result.

The Sirtex Medical Limited (ASX: SRX) share price has risen just a touch under 99% since the start of the year. The catalyst for this gain was a couple of takeover approaches for the regenerative medicine company from Varian and CDH Genetech. The latter appears to have been the victor and a deal appears to be nearing completion. If all goes ahead as planned, CDH Genetech will acquires all the shares of Sirtex Medical for A$33.60 per share, by way of a scheme of arrangement. This will take its year-to-date return to 103% upon completion.

The Specialty Fashion Group Ltd (ASX: SFH) share price has rallied an incredible 585% since the start of 2018. The fashion retailer’s shares were heavily sold off in 2017 after a disastrous performance and a failed takeover approach. This had many in the market questioning its ability to continue as going concern. However, a successful structural review and the offloading of five retail brands to Noni B Limited (ASX: NBL) has investors bullish again. Especially as Specialty Fashion retained ownership of its City Chic brand, which was the most profitable brand in its portfolio with strong historical earnings growth and an attractive outlook. Despite the mind-blowing share price rise, I still think it is one of the better options in the retail sector right now after this review.