One of Pimco's biggest public defenders was California pension fund Calpers, which had $1bn with Pimco but it was not managed by Mr Gross.
Charles Skorina, who runs a recruitment firm for the investment management industry, says the number of CVs and calls from disenchanted Pimco employees rose throughout the year. "It started with one, and then I had five, and by summer some 15 or 20," he says. "There was a good deal of unhappiness at a firm that before people were very keen to work for."
The 70-year-old Mr Gross showed no inclination to retire. He tweeted in January, "I'm Ready to Go for Another 40 Years", although it only served to focus attention on his age. At the same time, Pimco executives were pushing forward the next generation of portfolio managers, impressing upon nervous clients that Pimco had a deep well of talent beyond its founder and public face.
According to people familiar with the conflict, both sides appeared to believe that they were not being given enough credit for Pimco's success: Mr Gross for steering its successful investments for four decades, the other portfolio managers and business executives for helping diversify the company away from core bond funds such as Total Return into other fixed-income strategies that were popular among investors.
Despite his pledge to change his management style, Mr Gross continued to be prone to angry outbursts and put-downs of other executives, with many of these directed at Douglas Hodge, who had replaced Mr El-Erian as chief executive, and some at the man who replaced him as chief investment officer, Dan Ivascyn. Mr Gross declined to comment for this article.
Disappointment at the Pimco founder's behaviour coalesced when the firm's 240 portfolio managers from around the world met in Newport Beach for the quarterly "cyclical forum" to debate investment strategy. Executives feared they might be heading towards a choice between Pimco's founder and the managers on which they were pinning hopes for the long-term future.
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In surreptitious meetings, the executive committee canvassed support for Mr Gross. Several senior portfolio managers, including Mr Ivascyn, threatened to quit if he was not pushed out, according to people familiar with the events. The committee planned to confront and forcibly retire Mr Gross last Saturday but he discovered the plan and was already plotting his dramatic departure.
Last Friday morning, before even submitting his resignation, Janus Capital announced Mr Gross was joining immediately to run a start-up bond fund. It was an announcement that seemed calculated to cause maximum damage to Pimco, eschewing the usual niceties of smooth transitions and amicable handovers, catching the fund manager and its parent company Allianz flat-footed, not to mention stunning the investment world.
"I had to double-check there wasn't another William H Gross," says the chief executive of one big fund manager.
One email, from Chuck Manning at Eaton Vance to an investment manager, was typical of those arriving in Pimco clients' inboxes within hours of the announcement. "Bill Gross is leaving PIMCO," the email began. "Major news with potentially major ramifications for our industry . . . no question. From an asset management perspective, the first instinct is to reach out to every adviser and offer a substitute or compliment [sic] to Pimco Total Return. I'm sure you have received an incredible volume of such correspondence."
Executives worked through last weekend to react quickly by scrambling sales staff and preparing marketing materials. The efforts to gently prise clients away from Pimco, which had begun in January, intensified. Some clients jumped quickly to other managers, whereas larger institutional clients, true to form, are taking time to ponder. Calpers and other US public pension plans, such as those in New York and Florida, which are examining their holdings, could set the tone for others to follow.
The months-long process gives Pimco some breathing space to explain its new portfolio management structure under Mr Ivascyn as CIO and introduce the three new managers of Mr Gross's Total Return fund. It also offers time to persuade them that the firm's formal investment process is what has made Pimco successful, not the overlay of Mr Gross's famed investment instinct.
Mr Ivascyn told the Financial Times: "What we are trying to do is put together the best accumulation of ideas across the analysts teams and if we can do that well – and I always use the analogy of a conductor of an orchestra – then good things happen." For the present, outflows appear to be largely by retail clients and are focused on the Total Return fund, which suffered a record $23.5bn in withdrawals in September, more than 10 per cent of its assets.
But Pimco has to contend with a series of knee-jerk downgrades by consulting firms that could have knock-on consequences for its ability to retain some institutional clients. Mercer, one of the biggest pension fund consultants, told its clients that Mr Gross's old funds no longer deserved an A grade. Firms such as Western Asset Management, BlackRock, Loomis Sayles, JPMorgan and Goldman Sachs, with the scale to take over multibillion-dollar mandates from Pimco, are hoping to take advantage.
For some advisers, however, the departure of Mr Gross might eliminate some of the uncertainty and drama, especially if not having to pay his reputed $200m-a-year salary frees money to share among the troops.
Mr Woods of BPAS says he is happy having switched his $1bn to another west coast firm, MetWest, but admits to being tempted to nibble at Pimco once again – if it stays out of the headlines.
"As for whether we would consider moving to Janus? No way in hell. I'm done with Bill Gross. Bonds are meant to be boring."
Additional reporting by Tom Braithwaite