Goldman Sachs Group Inc. is lobbying regulators to exempt investment vehicles known as credit funds from the "Volcker rule" in a bid to preserve the firm's lucrative merchant-banking unit, the Wall Street Journal reported today. Goldman does have a backup plan if its lobbying plan fails as executives at the New York-based company believe they have found a way to extricate the credit funds from proposed limits on how much can be invested in hedge funds and private-equity funds. The Volcker rule, created by the Dodd-Frank Act caps a bank's total investments in hedge funds and private-equity funds at 3 percent of its so-called Tier-1 capital. It also prevents any single bank from accounting for more than 3 percent of a fund's investments. Since Congress passed Dodd-Frank, the financial-services industry has spent more than $330 million on lobbying, according to a Wall Street Journal analysis of expense filings that cite Dodd-Frank as an issue lobbied.