Japan-based Renesas Electronics Corp. /zigman2/quotes/203872935/delayed JP:6723 +2.53% is in discussions to buy Maxim Integrated Products Inc. /zigman2/quotes/201861354/composite MXIM +3.80% for what could be near $20 billion, CNBC reported late Monday. Maxim stock rose 12.6% to $66.43 during the regular session and was up nearly 1% to $67 after hours. Citing anonymous sources CNBC reported the talks aren't close to completion and a deal may not fall into place. Investors value Maxim at $16.61 billion by market capitalization. Maxim stock is up 62% this year, as the S&P 500 index /zigman2/quotes/210599714/realtime SPX +1.61% has gained 25%.