Since the 2008 financial crack-up, investment banks scaled back activity so firms were forced to slash leverage and rebuild capital buffers. Capital, like water, has a habit of finding its natural level, however some debt market activity has migrated outside the traditional banking circle.

This process has seen the rise of private credit - often this publication reports on former investment bankers setting up private debt boutiques. Private credit, its advocates say, generates better yields than conventional fixed income, although clients must accept lower liquidity and higher due diligence costs.

According to is a win-win situation - fund managers get to build stronger relationships with investors and increase their chances of successful fundraisings, while investors can benefit from cost savings, network expansion, and knowledge transfer,” Ken Yap, managing director, Asia at Cerulli Associates, said.

“Traditional managers looking to jump into co-investments will need to enhance their propositions and client servicing to compete with alternative specialists armed with years of experience and innovation," he said.

Arguably the easy wins for private debt investors have already been achieved, and as interest rates rise, practitioners must look harder for results.

That is certainly the view of Saranac's Cowter-Jones.

"As this cycle progresses, new investors will be forced to manage extensions, defaults and work outs. Given the strong bias to secured lending, investors recovery rates should remain moderate but whether the full risk of these structures has been priced in and how these positions will be managed post default is still to be tested. This is especially important as investors begin to position for late cycle opportunities – distressed credit and special situations. New managers in this space are likely to be major recipients of new capital to the debt market in 2019," he said.

A report last August by Preqin, a research firm tracking such assets, said there is so much unused money in parts of the private capital space - over $1.0 trillion of "dry powder" in private equity alone - that the sector may suffer from indigestion if the world economy slows down.