Cinch up that power tie under the hoodie.

Mark Zuckerberg is developing a “Facebook at Work” Web site, a report said — sending shares of professional networking company LinkedIn down 4.5 percent on Monday.

Facebook, the Menlo Park, Calif., tech giant, is developing a site for people to connect professionally, the Financial Times reported on Monday.

The site will initially be available to employees through their companies, the Wall Street Journal added. But LinkedIn dropped to $223.28 a share on fears that the service, slated to be launched in January, could eventually allow workers to make their Facebook at Work profiles public — thus treading on LinkedIn’s turf.

The new site will also compete with the likes of Google and Microsoft by allowing users to share and collaborate on documents over the site, the FT report said.

Facebook shares traded flat, closing down just 64 cents, at $74.24.

Zuckerberg’s expansion plans should come as no surprise. Last month, Facebook executives told investors to expect higher spending in coming quarters as the site ramps up its investments in engineering talent and acquisitions.

The Facebook CEO has been on a spending spree of late in an effort to expand and diversify the business, including the company’s $19 billion acquisition of messaging service WhatsApp.

While Facebook is best known as a way to communicate with friends and family, it has also morphed into a semi-professional tool, including public fan pages and the ability for users to “follow” people they are not friends with, but have an interest in.