materials relied upon by the opposing party do not actually establish the absence or presence of a genuine dispute. Fed. R.Civ.P. 56(c)(1). Conclusory assertions offered without any factual basis in the record cannot create a genuine dispute sufficient to survive summary judgment. Ass’n of Flight Attendants-CWA v. U.S. Dep’t of Transp., 564 F.3d 462, 465-66 (D.C.Cir.2009). Moreover, where “a party fails to properly support an assertion of fact or fails to properly address another party’s assertion of fact,” the district court may “consider the fact undisputed for purposes of the motion.” Fed.R.Civ.P. 56(e).
When faced with a motion for summary judgment, the district court may not make credibility determinations or weigh the evidence; instead, the evidence must be analyzed in the light most favorable to the non-movant, with all justifiable inferences drawn in his favor. Liberty Lobby, 477 U.S. at 255,106 S.Ct. 2505. If material facts are genuinely in dispute, or undisputed facts are susceptible to divergent yet justifiable inferences, summary judgment is inappropriate. Moore v. Hartman, 571 F.3d 62, 66 (D.C.Cir.2009). In the end, the district court’s task is to determine “whether the evidence presents a sufficient disagreement to require submission to a jury or whether it is so one-sided that one party must prevail as a matter of law.” Liberty Lobby, 477 U.S. at 251-52, 106 S.Ct. 2505. In this regard, the nonmovant must “do more than simply show that there is some metaphysical doubt as to the material facts,” Matsushita Elec. Indus. Co., Ltd. v. Zenith Radio Corp., 475 U.S. 574, 586, 106 S.Ct. 1348, 89 L.Ed.2d 538 (1986); “[i]f the evidence is merely colorable, or is not sufficiently probative, summary judgment may be granted,” Liberty Lobby, 477 U.S. at 249-50, 106 S.Ct. 2505 (internal citations omitted).
In recognition that it may be difficult for the plaintiff in an employment discrimination or retaliation action to uncover clear proof of discriminatory or retaliatory intent, the district court should approach summary judgment in such actions with “special caution.” Aka v. Washington Hosp. Ctr., 116 F.3d 876, 879-80 (D.C.Cir.1997), vacated on other grounds, 156 F.3d 1284 (D.C.Cir.1998) (en banc). Nevertheless, the plaintiff is not relieved of his obligation to support his allegations with competent evidence establishing that there is a genuine dispute of material fact. Brown v. Mills, 674 F.Supp.2d 182, 188 (D.D.C.2009). As is always the case, where the plaintiff will bear the burden of proof at trial on a dispositive issue, he bears the burden of production to designate specific facts showing that there is a genuine dispute for trial. Ricci v. DeStefano, — U.S.-, 129 S.Ct. 2658, 2677, 174 L.Ed.2d 490 (2009). Absent this burden, a party could effectively defeat the “central purpose” of the summary judgment device — “to weed out those cases insufficiently meritorious to warrant ... a jury trial” — simply by way of offering conclusory allegations, speculation, and argument. Greene v. Dalton, 164 F.3d 671, 675 (D.C.Cir.1999). With these principles in mind, the Court turns to the merits of the AOC’s Motion for Summary Judgment.
IV. DISCUSSION
Herbert challenges three separate employment actions in this action as discriminatory and retaliatory: the letter of reprimand; the alleged delay in his promotion; and the internal investigation. The Court’s discussion herein proceeds in three parts: (a) the Court shall first explain why no reasonable fact finder could conclude that these three employment 'actions were sufficiently adverse to support Herbert’s claims for retaliation; (b) the Court shall then turn to explaining why the same