Diluted EPS = Net Income / Fully-Diluted Shares Outstanding
Dilution is not automatically bad. If the cash raised from a secondary offering generates returns above the company's cost of capital, existing shareholders are better off after the dilution. The question is whether the deal is accretive (earns more per share than the share-count drag) or dilutive (earns less). A stock split is NOT dilution — every shareholder's count multiplies by the same factor, so your percentage ownership doesn't change. Dilution specifically refers to share count rising while your share count stays constant. For the full accretion-vs-dilution test, see ma-2 'Accretion/Dilution' (advanced).
Buybacks are the opposite of dilution — they SHRINK share count. But heavy stock-based compensation (paying employees in shares instead of cash) plus heavy buybacks can net to roughly zero — what some practitioners call 'treadmill buybacks' (the company is just running in place, buying back enough shares to offset SBC issuance without actually reducing share count). When companies advertise buyback-driven EPS growth, check whether net-of-SBC share count actually fell. For the full treatment of share-count math, see fsa-1 'EPS and Dilution' (accounting-201), val-3c 'Buybacks: When Returning Cash Beats Reinvesting It' (the inverse-concept primer), and ma-2 'Accretion/Dilution' (ma-301 advanced).
Sit with the ideas.
Coresight Robotics has 50M shares outstanding and earns $40M of net income (EPS = $0.80). To fund an R&D push, the company issues 10M new shares in a secondary offering at $20 each, raising $200M in cash. Management invests the $200M into new product development that is projected to add $30M in incremental net income per year. What is Coresight's new EPS (on existing earnings only, before the new products generate income), and is the deal accretive or dilutive on a forward-looking basis?