MINNEAPOLIS ( Stockpickr) -- Stocks have been quite resilient lately. As the first quarter of 2011 has come to an end, the market is perched near multiyear highs. It seems nothing can pierce traders' bubble of optimism.With the bullish moves, stock values have grown too. While the moves may have been justified by corporate profit growth, the question now is how sustainable will the growth be. We'll find out when earnings reporting season begins in earnest after the closing bell today with the release of profits from Alcoa ( AA). Related: 5 Stocks With Bullish Analyst Sentiment This earnings season will be an interesting period for investors. Will companies blow away current estimates? If so, stock prices are likely to move higher. Or will profits slip due to the pressures of competition and rising input prices that negatively impact margins? Fourth-quarter results were mostly positive, but there were some conflicting results that could be a sign of further trouble during the current reporting period. Investor seeking clarity from the mixed signals should keep their eye on these five stocks.