The meme stock rally continues, and one big shareholder cashed out.Shares of Opendoor Technologies (OPEN 9.94%) have resumed their rally after a brief pause last month. The stock jumped as much as 12.3% this morning and remained higher by 4.8% as of 12:05 p.m. ET. Opendoor has become the latest meme stock as retail investors continue to push it higher.That jump comes despite a recent Securities and Exchange Commission (SEC) filing showing that one large shareholder is cashing in on the rally. A meme stock b ...