Consolidation of holdings triggers mandatory public offer when acquisition breaches prescribed shareholding thresholds under takeover rules. Regulation 11 restricts further acquisition of shares or voting rights by an acquirer who, with persons acting in concert, already holds a substantial stake, requiring a public announcement before increasing voting rights beyond prescribed incremental limits or moving into higher consolidation bands; it allows a limited market-based exemption for modest open-market purchases (excluding bulk/block/negotiated/preferential deals) and permits consolidation with a public announcement to protect minimum public shareholding. The regulation treats acquisition as including direct and indirect purchases and provides a specific disinvestment exception for Public Sector Undertakings where stages, parties and disclosures are consistent.