Investec has maintained its 'buy' rating and 1,900p target price for emerging markets-focused lender Standard Chartered, saying that the stock remains its top pick in the banking sector.In a research report on Friday, the broker highlighted dealings by StanChart directors which have contributed to the stock's recent underperformance. Around 1.4m vesting shares, equivalent to 30% of the average daily volume, were sold by directors over the past two days as part of an annual block exercise. Analyst Ian Gordon said: "Of course we do recognise that directors in general have limited trading windows, that equity-based incentives now form an increasing proportion of overall pay, (especially for successful, highly profitable, high growth companies), and that Standard Chartered's directors remain heavily invested in the company, both in terms of individual shareholdings and unvested options. As such, we do not seek to argue that their interests are not properly aligned.Nevertheless, he said: "While we have a sense of frustration seeing such share sales at distressed prices, the good news is that this 'technical headwind' is over."Gordon highlighted StanChart's "unique growth profile" which translates to a 19% earnings-per-share (EPS) growth forecast this year despite a challenging first quarter.The stock - "bizarrely in our view" - is now one of the cheapest UK banks, trading at 9.7 times 2013 EPS versus HSBC which trades at 11.3 times 2013 EPS.StanChart's shares were up 0.09% at 1,540.45p in early trading on Friday.