Goldman Sachs Group Inc (>> Goldman Sachs Group, Inc.) has long been the go-to firm for companies defending against activists ever since the days when they were called corporate raiders.

But over the past few years, big banks like Credit Suisse and Barclays Plc (>> Barclays PLC) as well as investment bank Houlihan Lokey, which focuses on the middle market, have formed practices offering the services.

The banks help companies with everything from writing press releases to analyzing the costs of a breakup or countering activists' demands, bankers said. They are also aid companies in identifying where they could be vulnerable, even before activist investors show up on their doorsteps.

"The level of receptivity from companies has definitely increased," said Daniel Kerstein, head of the strategic finance group at Barclays. "In some cases the proposed medicine may be worse than the problem, but you are still going to listen."

Companies are increasingly coming under fire from activists. There were 241 activist campaigns in 2012 targeting a change in company strategy or board, up from 187 in 2009, according to FactSet SharkWatch.

Over the past three years, activist hedge funds have outperformed more traditional hedge funds, according to Chicago-based Hedge Fund Research (HFR). Its activist index has returned 3.80 percent on an annualized basis, compared with its global hedge fund index, up only 0.25 percent.

That has drawn the attention of investors. Assets under management in activist funds doubled to more than $65 billion in 2012 from $32 billion in 2008, according to HFR.

Successful activist campaigns, and the pressure to outperform index funds in a low-return environment, have made pension and mutual funds more willing to join up with activist investors, giving them more allies in their campaigns.

With the U.S. economy recovering, it is also easier to discern which companies are underperforming, making them more visible targets.

"The numbers are not going to retreat," said Chris Young, head of contested situations at Credit Suisse. Once investors see that activist campaigns are successful, "then that tool is identified as one of the tools in their toolbox."

For the investment banks, offering defense advice can help solidify relationships at the most senior level, such as a board of directors or top management, bankers said.

Barclays has grown its shareholder defense services over the past few years as an outgrowth of its equity restructuring business, which helps with non-distressed corporate breakups. The team sits within the bank's mergers and acquisitions practice, Kerstein said.

Credit Suisse hired Young, the former director of M&A and proxy fight at influential proxy adviser Institutional Shareholder Services, to head its takeover defense practice in June 2010.

"As a firm we've been devoting more resources and more headcount to this subject matter in an environment where banks in general have been decreasing headcount," Young said, declining to elaborate.

Houlihan Lokey, which focuses on mid-sized corporations, has expanded its business advising on activist defense over the past couple of years, said Gregg Feinstein, managing director and co-head of M&A. Unlike larger peers Goldman and Credit Suisse, Houlihan works with both activist funds as well as companies.

Being proactive is key, said Bill Anderson, head of the defense practice at Goldman. For example, companies are increasingly assessing potential vulnerabilities, even before activists show up.

Communicating with other shareholders - not just the activist investors - is also crucial, bankers said.

"Companies need to make sure they are talking to all of their shareholders on a regular basis," Kerstein said. "You want your shareholders to be brutally honest with you."

(The story corrects in paragraphs 3 and 16 name of firm to Houlihan Lokey not Houlihan & Lokey)

(Reporting by Jessica Toonkel; Additional reporting by Soyoung Kim; Editing by Jeffrey Benkoe)

By Jessica Toonkel