Amid concerns over profitability and competition for SL Green's massive One Vanderbilt project, two of the firm's top executives have purchased personal stakes in the development.

SL Green CEO Marc Holliday paid $1.44M for a 1.5% to 1.8% share in One Vanderbilt's profits, and president Andrew Mathias paid $960K for a 1% to 1.2% stake, The Real Deal reports. This comes mere months after SL Green spun off 29% of the building's equity to the National Pension Fund of South Korea and Hines to spread the risk of the $3B-plus project. Neither Holliday nor Mathias is permitted to sell his shares until the building is completed and fully leased.

While SL Green executives say the move reflects their confidence in the market, market experts contend the equity stakes give credence to doubters who think the project will struggle to achieve its financial goals.

Still only one major office tenant has signed a lease in the 1.6M SF tower adjacent to Grand Central Terminal: TD Bank, for a combined office and retail presence of 200K SF. SL Green executives told shareholders they do not expect leasing activity to begin in earnest until 2018, though they expect to attract $155/SF when it does.