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SpaceX plans to reserve up to 5% of its outstanding common stock for certain employees and individuals selected by its executive officers through a directed share program, the company said in an amended filing on Monday.

SpaceX said that if participants buy in, their stock will be free from the lockup requirements that constrain shares owned by corporate insiders. More than 60% of shares outstanding immediately prior to the offering are subject to an extended lockup period, according to Bloomberg, including stock held by founder and CEO Elon Musk, whose shares are locked up for 366 days after the final prospectus is filed.

As a general practice, directed share programs exist to give friends and family of a company or its executives access to IPO stock, according to MarketWatch. What sets SpaceX's arrangement apart is that the company is waiving a restriction it typically applies in such programs: most directed share participants elsewhere face lockup periods barring quick resales, Bloomberg reported.

Monday's amended filing put a concrete number on the directed share set-aside for the first time. The exemption from lockup requirements for those on the friends and family list had been signaled in earlier filings, but the actual size of the allocation was left unspecified until now.