You refuse to explain, but it looks to me like you're arguing...

You refuse to explain, but it looks to me like you're arguing that a 25,000 share ($15k) sell order at market is somehow manipulating the market by providing a substantial sell overhang in a $600m market cap company in the middle of a share buyback.

The only way this is a "blocking sell" is possibly in the intention of the seller. To the rest of the market, it's just a normal sell order, and as the lowest price sell order at the time it was facilitating trading opportunity rather than blocking it.

If someone wants to dump a 5% stake on market, that's a different story. We're talking less than 0.0025% of shares outstanding.

If there's anything that separates a blocking sell from a regular sell other than intended effect, let me know.