John Hancock investments have been widely praised as “the best books on the subject”.
And the company has been credited with creating one of the best-performing companies in the financial services sector.
John Hancock is now worth about $7bn.
Its latest earnings report was released on Friday and highlighted how the investment returns have improved in recent years.
The company has continued to invest heavily in new capital to support growth.
It has been a strong performer in the US market, where it has invested more than $1.5bn.
But analysts are also saying the company’s investment books have been heavily overvalued by some analysts.
Investors have also questioned how long the company will last as its investment books are not backed by a company.
John Halsey, chief investment officer at Berenberg, said the firm’s investment book was not strong enough.
“Its been overvalued in a way that is really hard to justify, and it’s a concern that the market hasn’t gotten more accurate about what’s going on with this company,” he said.
“The market is very, very concerned about it.”
Mr Halseys comments follow concerns about the company by several investors and analysts.
Investors are worried about the financial future of the company.
The stock was down 1.9 per cent to $8.96 on the Nasdaq on Friday.
Its shares have lost about $1bn in the past six months.
But it is still worth more than other large investors such as JP Morgan and Morgan Stanley.
The firm said the earnings performance of its investment book in the last 12 months was positive and had been consistently well outperformed by the S&P 500.
The company’s management has also improved its capital position, with its cash pile at $2.3bn.
Investor concerns over the future of its business and investment books come after the company recently released an investment report that suggested its investment performance was not as strong as its analysts had hoped.