What happened Shares of space stock AST SpaceMobile (Nasdaq: ASTS), which went public in a SPAC-sponsored reverse merger last week, have declined more or less steadily ever since that event took place. They're down again today -- 9.9% as of 1:30 p.m. EDT. So what To refresh your memory, New Providence Acquisition touted AST SpaceMobile stock as a play on a "$1 trillion global mobile wireless services market" in which "five billion" potential customers would like to be able to use their ordinary cellphones to place calls via satellite. AST promised to make that happen by launching a constellation of satellites to carry the calls, using technology that "is highly proprietary" -- so much so that the company declined to disclose "exactly how it works." Despite this rather glaring omission, AST won the endorsement of noted short-seller Citron Research in February. They reasoned that "all SPACS are speculative," so "why not [at least] go with one with a [claimed] $1 trillion" total addressable market? Image source: Getty Images. Now what But that leap of faith isn't going very well for Citron Research so far. From $22.50 a share on Feb. 9, when Citron endorsed the investment in the form of the NPA SPAC, newly public AST stock has now lost more than half its value, plummeting below $9 a share. Will AST be able to recover? According to company CEO Abel Avellan, speaking on CNBC last week, AST raised enough money from its IPO to launch the first 20 satellites of its planned constellation. No word yet on precisely when those satellites will launch, however, or how soon after launching they'll be able to begin generating revenue for AST. Until we get more specifics on that front, I suspect AST stock may continue to slump. 10 stocks we like better than WalmartWhen investing geniuses David and Tom Gardner have an investing tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now… and Walmart wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks Stock Advisor returns as of 2/1/20Rich Smith has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source