REUTERS/Vasily Fedosenko
Investors are worrying how the company will deal with its huge debt pile, $100 billion (£658 million), as copper prices fall. Glencore is not especially profitable.
But on Tuesday Citi told investors to buy shares in Glencore, saying "the market's response is overdone."
And it added that if investors can't see that then Glencore's management should take the company private.
Glencore shares opened up as much as 6% in London on Tuesday following the note.
They're now trading up over 9% at 10.18. a.m. BST (5.18 a.m. ET).
Investing.com
But if Glencore is going private it might mean a payday for any brave investors willing to buy in now. Glencore issued new shares at £1.25 ($1.90) earlier this month and Citi sets a target price of £1.70 ($2.58). Shares closed on Monday at 69.17p ($1), so clearly shareholders could demand a premium.
Here's the key paragraph from Citi:
We believe that in the event the equity market continues to express its unwillingness to value the business fairly, the company management should take the company private, whereby restructuring measures can be taken easily and quickly, with a potential float of just the industrial business occurring further down the track.
Citi thinks the close to 60 banks dealing with Glencore are unlikely to pull credit lines unless there is a credit rating change, which it also thinks is unlikely. Glencore's trades and mining inventory are also largely hedged, so big price falls shouldn't have a corresponding effect.
CEO Ivan Glasenberg still owns just shy of 10% of Glencore, so the lower the price drops, the worse it gets for him. On Monday he lost $500 million (£329 million) in paper value alone.
And shares are more likely to go up than down. Since listing in 2011 at £5.30 ($8), Glencore's share price has more or less been a straight slide downward. Investors find it hard to wrap their heads around the complexities of the business.
It might make sense to take Glencore private then.
It's worth bearing in mind through all this that Citi may have a dog in the fight - the investment bank was one of two running the $2.5 billion (£1.65 billion) rights issue earlier this month and also helped run the company's 2011 IPO.