Lloyds has underperformed the European banking sector by 8% in the year-to-date, but Evolution Securities says that the bank remains its "top conviction buy" because - beyond short-term risks - the rewards for investors are striking.However, Evolution notes that the short-term outlook is plagued with uncertainties: "The next few months will see a large kitchen-sinking exercise [primarily due to additional Irish impairments, and potential payment protection insurance contingencies], the recommendations of the ICB, and the sale of the 600 branches. Certainly a hectic schedule which, together with other key issues such as the impact from higher UK rates, has scared investors," the broker said.Nevertheless, the medium term remains very bright with the group having a very clear roadmap towards a 20% group return on equity."Lloyds is the only bank in our coverage where we think investors might have a realistic chance of doubling their money, on an 18-24 month view."The new target price of 106p has a 77% upside, according to the broker.