public async Task <Dictionary <string, List <string> > > ProcessAsync(DateTime date)
{
var stockPrices = await _stockPriceService.GetStockPricessByDateAsync(date);
return(stockPrices
.GroupBy(s => s.Exchange)
.ToDictionary(g => g.Key, g => g.Where(x => x.DailyGain == g.OrderByDescending(y => y.DailyGain).First().DailyGain).Select(z => z.Symbol).ToList()));
}