What happened

Shares of Virgin Galactic Holdings (SPCE -12.17%), which exploded higher on the promise of a test flight Monday, are dropping back to Earth today -- down 4.9% as of 11:45 a.m. EST.

The reason: Virgin Galactic is rapidly facing increased competition in the space sector.

Blackboard drawing of stock chart arrow going up being erased and pointing back down

Image source: Getty Images.

So what

Celebrated at its 2019 IPO as "the world's first and only publicly traded commercial human spaceflight company," Virgin Galactic technically still holds that title, but the distinctions are starting to pile up. The past few months have given us the promise that the first "space tug" company, Stable Road Acquisition's (SRAC) Momentus, will go public. That announcement was followed in short order by the announcement of the first satellite-driven communications network for ordinary mobile phones: New Providence Acquisition's (NPA) AST SpaceMobile.

Today, a fourth potential pure-play space stock emerged, when special purpose acquisition company Holicity (HOL) announced that it will bring small rocket company Astra public through a reverse merger.

Now what

Stable Road, New Providence, and Holicity have yet to finalize their mergers. That means Momentus, SpaceMobile, and Astra have yet to officially IPO.

But clearly, the momentum is moving in this direction, and the days when Virgin Galactic founder Sir Richard Branson can boast that buying Virgin stock is the best way to "dabble a little bit in a spaceship company, own a little bit of a spaceship company," are coming to an end. One day soon, investors may cease investing in space for the novelty factor, and have to begin weighing revenues and profits -- and price -- to determine which space stock is the best bargain.  

Whether Virgin Galactic will remain top dog in that kind of contest has yet to be seen.