Under Article 28(1)(b) of Regulation (EU) No 575/2013 (CRR), capital instruments shall qualify as Common Equity Tier 1 (CET 1) instruments only if the instruments are fully paid up and their purchase acquisition of ownership of those instruments is not funded directly or indirectly by the institution. The last subparagraph of this Article  28(1) CRR further also clarifies that for the purposes of Article 28(1)(b) CRR only the part of a capital instrument that is fully paid up shall be eligible to qualify as a CET1 instrument.The purpose of this condition is to ensure that the institution has genuinely received new funds at issuance.
Articles 8 and 9 of the Commission Delegated Regulation (EU) No 241/2014 (RTS on Own Funds) specifyies the applicable forms and nature of direct and indirect funding.

The EBA is mandated in accordance with Article 28 (5) (a) of CRR to develop draft regulatory technical standards (RTS) to specify the applicable forms and nature of indirect funding. The example laid out in this question will have to be assessed against the future RTS to determine whether it has to be considered as direct or indirect funding.

If the criteria set out in the final adopted RTS are met, tThe following treatment should applyies if the acquisition of ownership of shares involves direct or indirect funding:
At issuance firms exclude the accounting value of the instruments (and associated share premium accounts) in accordance with Article 28(1)(b) of the CRR as further specified in Articles 8 and 9 of the RTS on Own Funds; this reflects that there is no real increase of capital to add onto the institution's balance sheet.
On the basis of the above at issuance the questions 1) to 4) are answered as follows:
CET 1 instruments contribute to CET 1 capital at their accounting value and only in relation to the amount that has been fully paid-up. In the case an instrument does not meet the CET 1 criteria in Article 28 of the CRR, or ceases to meet CET 1 criteria, as set out in Article 30 of the CRR, the accounting value of the instrument shall be excluded from contributing towards the CET 1 capital of the institution. Therefore, where direct or indirect funding has occurred at issuance, the accounting value of the instrument purchased with direct or indirect funding shall be excluded from contributing to CET 1.
1) The amount that the institution shall exclude from CET 1 is the accounting value of the shares, which in this example is 200.
2) Since the amount that is excluded is the accounting value, a change in the market value of the shares has no bearing. Likewise, the amount of the loan relative to the share value has no bearing.  So, in the example, the relevant amount to exclude is still 200.
3) The posting of collateral is not a relevant consideration when judging whether or not direct or indirect funding has occurred. The holding of collateral could become relevant to the extent that the operation qualifies as a synthetic holding under Article 4 (126) of the CRR, which is the subject of a separate question (Q&A 2013 009).
4) At issuance, impairment should, in principle, not be of relevance to the extent that the funding/loan cannot be subject to impairment at inception. Where impairment arises, the treatment below applies will have to be applied.

After initial issuance, where firms directly or indirectly fund the purchase of their own fund instruments, likewise the accounting value of the shares is to be eliminated/derecognised since the issue revolves around the eligibility of the instruments rather than the loan exposure. Accordingly, the answers to scenarios (1) to (3) would be the same as above. For scenario (4), where the funding/loan is subject to impairment, the amount deducted should be net of any impairment allowance associated with the funding provided. Accordingly, the amount to be excluded from CET 1 shall be the accounting value of the instrument funded, less any impairment allowance associated with the funding, up to the point that the amount to be excluded nets to zero.
In case the amount of funding provided is higher than the accounting value of the instrument, the impairment amount to be considered should be proportionate to the share of the impairment in the funding.