Financing for US independent oil companies slowed sharply last year, in a sign of growing financial pressure following the plunge in crude and natural gas prices. US exploration and production companies raised just $3.26bn from equity sales in the second half of last year, down from $14.6bn in the first half, according to Dealogic, the information service. The companies, which led the US shale oil and gas boom over the past decade, also raised $4.57bn from issuing bonds from July to December, down from $23.9bn in the first half. Financial constraints are forcing companies to continue to cut capital spending, which is expected to result in lower US oil production.