Bond sales are at a record, equity markets are at year-highs, private equity firms are sitting on huge cash piles -- Blackstone alone has $29 billion -- and banks are lending to each other again.

The ingredients should all be there for a resurgence of cash-driven mergers and acquisitions. But instead, the market is in hibernation.

So far the value of all M&A deals completed this year totals $990 billion. You have to go back to 2003 -- when the total for the year was $1.23 trillion -- to find a figure this low, according to Thomson Reuters data.

Of this, some $364 billion -- just 37 percent -- were cash deals, marking a dramatic shift in the mix of recent years when cash has dominated.

The main spanner in the works is the still dire state of banks' balance sheets and the crippled syndicated loan market. This has kept a tight lid on cash bids of any size, with the mega merger or takeover a distant memory.