Retail investors who spent weeks defending SpaceX through its post-IPO run turned net sellers on Friday, marking the first such instance since the company's blockbuster debut in June.Mom-and-pop traders sold a net $4.5 million in Elon Musk's rocket company on ‌August 7, the ⁠first ⁠net negative reading since the company went public on June 12, according to Vanda Research data."A shift from persistent net buying to selling is rarely about one catalyst, it is usually a mix of profit-taking, position fatigue and investors reassessing the risk-reward," said Sam North, market analyst at etoro."Friday is particularly interesting because retail turned net sellers while the shares were rebounding strongly and trading back around the IPO price. That looks more like investors using strength to ​take some money off the table than panic selling."By comparison, the ⁠highest single-day ‌net buying in SpaceX's trading history reached $144.6 million on June 16, suggesting the outflow ​remains modest by ​the stock's own standards.This comes just days after individual investors "bought the dip" as ⁠shares slumped 13.6% on August 5, when retail net-buying was the fourth-highest ​since the company's June debut.Shares had dropped as investors reacted to SpaceX's first-ever quarterly earnings report as a public company, in which it touted faster returns from AI spending, but concerns remained about how long its profitable Starlink business would bankroll costly AI investments.The reversal in sentiment tracks a broader unwind in SpaceX's share price. The stock surged as much as 67% above its $135 IPO price in June before giving back all of the gains and falling more than 22% ‌below its debut price in August.Shares were last up 1.4% at $134.95 in early trading after surging nearly 23% last week.Despite the recent jump, its shares have closed ​below the IPO price ​every day since July 16.Small ⁠investors have been crucial in the company's history on the public markets, as at least 30% of shares that were made available on debut were set aside for retail buyers.Jai Malhi, senior equities strategist at Vanda, estimates that retail traders on average paid $147 for SpaceX shares since the IPO, so "the selling may have been a function of cutting losses at an opportune time."In the last one week, SpaceX was the second most mentioned ticker on Reddit forum r/WallStreetBets, per sentiment aggregator SwaggyStocks.Liquidity conditions have also shifted as the number of SpaceX shares available for public trading more than doubled following the expiry of the first of several lockup restrictions last week.