A plateauing auto sales in the US and a slump in the Chinese market are conspiring to create a big headache for GM's top brass, especially Mary Barra.

The CEO has been in power for five years and despite returning $25 billion to shareholders through dividends and stock buybacks and selling off money-losing subsidiaries, some activist shareholders think a third major action is required in just four years.

The investors are asking what more the CEO can do now that stock prices at GM have fallen by about 6% from the initial share price at which they launched in 2010, according to a report from Reuters.

And without a founding family in control of the company, GM's options for defending itself from shareholder actions is limited.

While many investors wonder what GM could do differently, other think that the company could be spinning off its brands, getting out of the sedan game, and doing more with Cruise Automation. Some, like Barometer portfolio manager Jim Schetakis, are even going as far as to say that Barra should be taken out of her role.

"The board has to walk out to the mound and take the ball away," he told Reuters.

[source: Reuters]