Dutch financial authorities have announced that trading in Spyker shares has been suspended, prompting speculation that a deal to purchase Saab is about to be announced.
This is a common move before a company announcement during trading hours.
Swedish news channels are quoting Spyker boss Victor Muller as saying, "I can't comment now, but there will definitely be an announcement later today."
Earlier today Spyker's chief executive admitted talks to buy Saab "could go either way".
Muller is holding talks with GM in Sweden at the moment, and told the Reuters news agency, "Negotiations are ongoing and the spirit is positive, but we are very, very tired.
"It is such a complicated transaction. It's not for no reason it has taken so long. It is extremely technical. It can go either way, but you can rest assured we are doing everything to close the deal."
Reports suggest Spyker will give GM $75 million (£47m) for Saab, while GM will keep another $100m (£62m) in current Saab liquidity, and $325m (£210m) in preferred shares from the new, Spyker-owned Saab company.
Spyker is now the sole bidder after investment company Genii Capital, backed by Formula One mogul Bernie Ecclestone, withdrew its offer on Monday.