shares fell in the extended session Wednesday after the aluminum company’s quarterly results topped Wall Street expectations but it warned that performance could worsen should its markets not recover. Alcoa shares declined 3% after hours, following a 1.1% decline to close the regular session at $22.84. The company reported a fourth-quarter loss of $4 million, or 2 cents a share, compared with a loss of $303 million, or $1.63 a share, in the year-ago period. Adjusted earnings were 26 cents a share, versus a loss of 31 cents a share in the year-ago period. Revenue declined to $2.39 billion from $2.44 billion in the year-ago quarter. Analysts surveyed by FactSet had forecast earnings of 11 cents a share on revenue of $2.38 billion. For the first quarter, Alcoa said it expects “lower quarterly performance” in both its bauxite and aluminum segments should markets not improve.