Stocks gained for a second straight week as earnings reports started to come in, keeping the S&P 500 index within a fraction of its highest level in five years. Companies have started to report fourth-quarter results, but no clear pattern has emerged as yet. Aluminum company Alcoa gave stocks a lift after it reported earnings that matched analysts’ expectations and said that demand was increasing. Investors were unimpressed by Wells Fargo’s record profits. Companies reporting earnings this week include ­JPMorgan Chase, Goldman Sachs, ­Citigroup, Bank of America, as well as eBay, and Intel.