It has been nearly a month since Sharp accepted Foxconn's more than 600bn yen (Â£3.7bn; $5.4bn) offer, but no final agreement has been signed.
According to reports, Foxconn is looking to reduce the price it pays.
Japan's benchmark Nikkei index, on which Sharp is listed, closed up 1.9% at 17,048.55 on Tuesday.
Elsewhere, Asian stock markets had a mixed day.
In South Korea, the Kospi index ended 0.35% higher at 1,996.81, while in Australia the S&P/ASX 200 shed 0.3% to close at 5,166.62 after data showed house price growth cooled in the final three months of 2015.
Stocks in China snapped their recent winning streak. Markets had rallied on Monday after China relaxed margin trading rules, but on Tuesday the Shanghai Composite closed down 0.6% at 2,999.36.
In Hong Kong, the Hang Seng index ended the day down 17.40 points at 20,666.75.
Shares in Japanese electronics firm Sharp have fallen by 6.5% on concerns a delayed takeover deal with Taiwan's Foxconn may fall apart.