Commercial real estate stocks are bouncing back this week after taking a big hit. Shares of SL Green, Manhattan's biggest office landlord, are up 14 percent. On Monday, SL Green unveiled a $3 billion, 77-story new office tower in midtown, showing the company is betting on a future that includes workers going back into the office. Andrew Mathias, president of SL Green, joins "Squawk Box" to discuss.