private IEnumerable <Price> GetNewPrices(IEnumerable <Price> allPrices) { var lastPrices = PriceRepository.GetLastPrices().ToList(); return(allPrices .Where(i => (lastPrices .Any(l => l.MarketId == i.MarketId && l.Value != i.Value) || (lastPrices.All(l => l.MarketId != i.MarketId)))).ToList()); }