No one is "accumulating relentlessly" 100 shares at a time, unless they're a fan of racking up needless trading fees and maybe commissions. Even with free commissions they're still going to get charged trading fees for each trade. This is just market makers playing games trading shares back-and-forth, in my opinion. To flood the tape with red numbers to try to create panic-selling. Every now and then they hit the Ask with a trade because they think that makes it less obvious, but usually that trade is under 100 shares so that it doesn't move the price. Then they go right back to making 100 share trades on the Bid.